I want to drawing in 3D but i don't know which is the best tool. I heard about solidworks tool then solidworks is better and cost effective then autocad software.
Depends on what your requirements are; solidWorks is great mecanical software, automatically updating the 2-D Drawing when the 3-D model is modified which is very useful. This is one of the main advantages of SolidWorks. There is an array of CAD software, all useful for different things. What is it that you are wanting to model?