The shadows of the meshes have many weird distortion.I tried to increase lightmap resolution of the mesh,but unfortunately it didn’t work.I really want to figure out what’s the problem.
The two screenshots below are what the shadows look like with stationary lights.
The reason you’re having issues is that your lightmap resolution is too low (or your mesh doesn’t have enough UV space allocated to the parts of the mesh receiving the shadow). In general, you should aim for at least green in the lightmap density view. The fact that your view is blue indicates a lack of resolution.
Here’s an example of the shadow quality differences between blue and green:
Oh I got it!Thanks a lot!I fianally realize what caused the problem!I tried to increase lightmap resolution of the meshes,and the color of them turned into green,but after I started baking,my computer froze 
！So I don’t know if there are other ways to increase lightmap resolution,can i scale the models to smaller one and fix the problem?
It looks like you are using a rescaled cube to build your level geometry. This is convenient, but using highly rescaled meshes like this results in very uneven lightmap resolution, so you end up with too much resolution on the short sides and not enough on the surfaces that require it.
The solution is to make a custom mesh with an efficient UV layout for lightmaps:
Here is a comparison of the lightmap UV layouts:
As you can see, my custom mesh has virtually all of the lightmap resolution allocated to the top face, allowing me to get high quality with a lower lightmap resolution. The default cube on the other hand, has more area dedicated to UV padding, and the same amount of texture space dedicated to each side because it was assumed it would be used as a cube.
Oh!Thank you very much 
!I checked the lightmap uvs,and changed some parameters,I finally got the baked shadows I want!
