diff --git a/ballance_blender_plugin/__init__.py b/ballance_blender_plugin/__init__.py
index 08e4df7..90ae879 100644
--- a/ballance_blender_plugin/__init__.py
+++ b/ballance_blender_plugin/__init__.py
@@ -19,7 +19,9 @@ if "bpy" in locals():
         importlib.reload(floor_rail_uv)
     if "utils" in locals():
         importlib.reload(utils)
-from . import utils, bm_import_export, floor_rail_uv
+    if "config" in locals():
+        importlib.reload(config)
+from . import config, utils, bm_import_export, floor_rail_uv
 
 # ============================================= func block
 
diff --git a/ballance_blender_plugin/bm_import_export.py b/ballance_blender_plugin/bm_import_export.py
index 3ad5692..f36a9c5 100644
--- a/ballance_blender_plugin/bm_import_export.py
+++ b/ballance_blender_plugin/bm_import_export.py
@@ -2,6 +2,7 @@ import bpy,bmesh,bpy_extras,mathutils
 import pathlib,zipfile,time,os,tempfile,math
 import struct,shutil
 from bpy_extras import io_utils,node_shader_utils
+from . import utils, config
 
 bm_current_version = 10
 
@@ -230,6 +231,7 @@ def export_bm(context,filepath,export_mode, export_target, no_component_suffix):
     # ====================== export texture
     ftexture = open(os.path.join(tempFolder, "texture.bm"), "wb")
     source_dir = os.path.dirname(bpy.data.filepath)
+    existed_texture = set()
     
     for texture in textureList:
         # write finfo first
@@ -245,9 +247,11 @@ def export_bm(context,filepath,export_mode, export_target, no_component_suffix):
         if (is_external_texture(filename)):
             write_int(ftexture, 1)
         else:
-            # copy internal texture
+            # copy internal texture, if this file is copied, do not copy it again
             write_int(ftexture, 0)
-            shutil.copy(texture_filepath, os.path.join(tempTextureFolder, filename))
+            if filename not in existed_texture:
+                shutil.copy(texture_filepath, os.path.join(tempTextureFolder, filename))
+                existed_texture.add(filename)
 
     ftexture.close()
 
@@ -280,7 +284,10 @@ def get_component_id(name):
     return -1 # todo: finish this, -1 mean not a component
 
 def is_external_texture(name):
-    return False # todo: finish this. external mean no copy file
+    if name in config.external_texture_list:
+        return True
+    else:
+        return False
 
 def mesh_triangulate(me):
     bm = bmesh.new()
diff --git a/ballance_blender_plugin/config.py b/ballance_blender_plugin/config.py
new file mode 100644
index 0000000..1c9b7f0
--- /dev/null
+++ b/ballance_blender_plugin/config.py
@@ -0,0 +1,85 @@
+external_texture_list = set([
+    'Ball_LightningSphere1.bmp',
+    'Ball_LightningSphere2.bmp',
+    'Ball_LightningSphere3.bmp',
+    'Ball_Paper.bmp',
+    'Ball_Stone.bmp',
+    'Ball_Wood.bmp',
+    'Brick.bmp',
+    'Button01_deselect.tga',
+    'Button01_select.tga',
+    'Button01_special.tga',
+    'Column_beige.bmp',
+    'Column_beige_fade.tga',
+    'Column_blue.bmp',
+    'Cursor.tga',
+    'Dome.bmp',
+    'DomeEnvironment.bmp',
+    'DomeShadow.tga',
+    'ExtraBall.bmp',
+    'ExtraParticle.bmp',
+    'E_Holzbeschlag.bmp',
+    'FloorGlow.bmp',
+    'Floor_Side.bmp',
+    'Floor_Top_Border.bmp',
+    'Floor_Top_Borderless.bmp',
+    'Floor_Top_Checkpoint.bmp',
+    'Floor_Top_Flat.bmp',
+    'Floor_Top_Profil.bmp',
+    'Floor_Top_ProfilFlat.bmp',
+    'Font_1.tga',
+    'Gravitylogo_intro.bmp',
+    'HardShadow.bmp',
+    'Laterne_Glas.bmp',
+    'Laterne_Schatten.tga',
+    'Laterne_Verlauf.tga',
+    'Logo.bmp',
+    'Metal_stained.bmp',
+    'Misc_Ufo.bmp',
+    'Misc_UFO_Flash.bmp',
+    'Modul03_Floor.bmp',
+    'Modul03_Wall.bmp',
+    'Modul11_13_Wood.bmp',
+    'Modul11_Wood.bmp',
+    'Modul15.bmp',
+    'Modul16.bmp',
+    'Modul18.bmp',
+    'Modul18_Gitter.tga',
+    'Modul30_d_Seiten.bmp',
+    'Particle_Flames.bmp',
+    'Particle_Smoke.bmp',
+    'PE_Bal_balloons.bmp',
+    'PE_Bal_platform.bmp',
+    'PE_Ufo_env.bmp',
+    'Pfeil.tga',
+    'P_Extra_Life_Oil.bmp',
+    'P_Extra_Life_Particle.bmp',
+    'P_Extra_Life_Shadow.bmp',
+    'Rail_Environment.bmp',
+    'sandsack.bmp',
+    'SkyLayer.bmp',
+    'Sky_Vortex.bmp',
+    'Stick_Bottom.tga',
+    'Stick_Stripes.bmp',
+    'Target.bmp',
+    'Tower_Roof.bmp',
+    'Trafo_Environment.bmp',
+    'Trafo_FlashField.bmp',
+    'Trafo_Shadow_Big.tga',
+    'Tut_Pfeil01.tga',
+    'Tut_Pfeil_Hoch.tga',
+    'Wolken_intro.tga',
+    'Wood_Metal.bmp',
+    'Wood_MetalStripes.bmp',
+    'Wood_Misc.bmp',
+    'Wood_Nailed.bmp',
+    'Wood_Old.bmp',
+    'Wood_Panel.bmp',
+    'Wood_Plain.bmp',
+    'Wood_Plain2.bmp',
+    'Wood_Raft.bmp'
+])
+
+component_list = [
+    
+]
\ No newline at end of file