How to import psk psa files in Unity3D?,Is there a way to import .psk or .psa files in Unity3D???

psk / psa files are used exclusiv in unreal engine. Unity does not support them. If you have the original model files you imported into unreal engine that could work with unity.

I'm probably a bit too late responding with respect to the OP, but I have had troubles with this myself, and I don't doubt many other people have been (and will be) as well.

https://developer.blender.org/T48800

I have had some success in getting psk and psa file data into Unity, but it hasn't been easy. You may just be able to use the PSA and PSK importers in Blender (a free 3D creation program), and then export them as FBX files, which can then be imported into Unity. However, I am not sure if the importers for Blender were created correctly, as after I attempted to import a PSA file into Blender, the bones of the file appeared to be rotated incorrectly, sticking out from the model instead of staying inside the model's mesh. Then again, my experience with PSA and PSK files is quite limited; the bones may have just been created as "control" bones in the file, and thus don't need to stay inside of the mesh. Ultimately, I was able to get the model to animate in Unity, but the animations tended to either rotate the model 90° along the X axis, or be too slow. So, it will take some fiddling around with them to get them right.

Alternatively, you could go even further and start off using Epic's Unreal Development Kit 3 (or UDK3). I'm not sure where you can get it from at the moment (it was once a free download, but not available any longer). If you manage to find it and download it, you can use it to open PSA and PSK files with and play around with the animations. It can also export the data out into FBX files, which both Blender and Unity can use. Since it was Epic that developed the PSA and PSK file formats in the first place, UDK would arguably the best programming environment to start with, as it should recognise PSA and PSK files better than any other program. However, it doesn't seem to offer very much on how an FBX file is exported. As an example, if you adjust the frame rate, export as FBX and then import it again into either Blender or Unity, it doesn't seem to change the frame rate at all.

Years after starting work on this (and work on and off of it), I have yet to create a proper workflow for importing such data into Unity, but I hope to get there very soon.