The study on bead on plate (BOP) and butt laser welding characteristics of AZ31B-H24 magnesium alloys are carried out by using two lasers, fiber laser and CO2 laser. The effect of different lasers on characteristics is analyzed, from the point of the weld appearances, microstructures and mechanical properties. The results show that fiber laser welded joint has good weld appearance and better suitability. Tensile strength of it can reach 95% of that of base metal, fracture is typically ductile feature, in which dimple is big and deep, while CO2 laser welded joint tends to arise porosity, which sharply decreases its tensile strength, only 47.6% of that of base metal. Fracture mode is mixed mode including ductile and cleavage mode.