Abstract: Active fluxes with four components (TiO₂, SrCl₂,ZrO₂ and Y₂O₃) were developed based on the requirements of A-TIG welding of AZ31B magnesium alloy on active fluxes, including weld penetration,weld appearance,mechanical properties and reinforcement mechanism of weld,process feasibility and non-toxic etc. The composite active fluxes were designed by uniform design method. A mathematical model was established according to the weld penetration depth and weld appearance. The optimized ingredients of active fluxes were determined and verified through the comparative analysis with different mathematical models. The results show that the maximum penetration could be obtained with good weld appearance and the welded joint had excellent mechanical properties,when the active fluxes was designed with the proposed uniform design method.