Could anyone tell me what is better in DX7? I think the triangle strip is faster because the vertices is less. I don''t know why the triangle list is faster in my program!!! Thanks.

Read this: DirectX Developer Faq, especially on vertex buffers.

DirectX is optimized for batch rendering, i.e. you should try to render as much as possible with every call to DrawPrimitive() or DrawIndexedPrimitive(). Triangle strips are faster than triangle lists for an equal number of triangles. However, with triangle strips you may have to make several calls to DrawPrimitive(), but with triangle lists all triangles can be drawn with one call.

(As a sidenote, several trianglestrips can be concatenated by adding some degenerate triangles between them. Personally though, I don''t like this approach.)