The research of welding parameters, such as surface absorption rate, laser power, welding speed on laser welding process, weld depth and weld width are discussed by means of finite element simulation. In the article, it takes 5A06 aluminum alloy welding as the example to build the finite element model. Finite element model can forecast the weld shape under different welding parameters, and can realize choosing and optimizing laser welding parameters to show the advantage of aluminum alloy laser welding.