I want to display the injection with the whole geometry together, but the color for whole geometry would always cover on the particle injection, that makes it's hard to judge the path of the particle. How to resolve it?

hi friend ur problem is so interesting me. I hope i will resolve ur problem very soon. first of all u do one thing. dont worry about color when u want to same as like bmp. first u go to file , hard copy , no color . check it like that

I think what you are talking about is the need for wall transparency. Go to scene, select the wall in question, and set the transparency. You probably will need to consult the help files.