How to create model with this type of typography in blender? I tried using single vertex to make the curve and then fill it until it become a flat plane. I extrude the plane and add subdivision modifier but the result ain't smooth.
Blender's curves don't support branching (not without some really extreme difficulty) so I don't think we want to use curve objects to do this. Instead, we can use a skin modifier to make these kind of branching letters:
I start with geometry that is just a string of verts (pictured on the right), give that string a single level of subdivision to smooth/curve it a bit, then give it a skin modifier to create the geometry. Then I can tune the radius of each vertex in edit mode to eye, using ctrl a. A final subdivision modifier adds additional geometry after the skin to smooth everything out nicely.