How to load 2D image?

I use matplotlib to draw some iamges, at the same time I have some .vtk files, is it possible to visualize them together in paraview?

Yes, Paraview can read PNG and JPG image and you can display them with VTK data in the same render view.

You may look at the tutorials to understand how to load and display data: 2. Basic Usage — ParaView Documentation 5.10.0 documentation