Abstract: Six kinds of analytically pure compounds, SiO2, MnO2, CaO, TiO2, CaF2, and NaF, were used to make multi-component active fluxes. 500 m thick of GH4169 superalloy sheets were welded by active laser welding process using micro pulse laser equipment. Effects of fluxes on microstructure and mechanical properties of the joints were investigated and discussed. The results showed that the weld bead penetration was increased by all 20 series of active fluxes compared with conventional laser welding. The effect of series F12 was especially notable and the increment of depth to width ratio of the weld was 159%. It is feasible to increase weld penetration thus to improve welding efficiency and reduce welding consumption using active fluxes. Microstructures in active laser welding seams were columnar and equiaxed grains and the joint tensile strength is 927 MPa, which was 92.7% of the base metal strength.