How can I make this kind of 3D paint stroke? Is it photoshop or C4D. please guide me through the process.
Can't say for sure, of course, but it looks to me like it was most likely produced in a 3D DCC tool, and yes C4D would work.
The three linear or curvilinear "brushstrokes" look like simple box modeled meshes, which were then distorted through a curve (mograph I'm sure) and each has a shader / texture applied which is the brush stroke, created in either PS or Illus, with an alpha channel for transparency to get the ragged rear end of each stroke. Each has a slight thickening at the forward edge, but other than that they are pseudo-2D folded to give the 3rd dimension.
The larger splatty mass looks sculpted, and there are many ways to approach that feel - what give all these elements the cohesion and the look is the paint stroke textures, and there's another Stack Exchange Graphic Design answer out there about that sort of thing:
It's also quite possible this was all done in Photoshop or similar, with brushes, and careful application of shadows and highlights to give the 3D feel.