The invention discloses a welding flux used in cooperation with strip surfacing nickel-based alloy welding strip with excellent crack resistance, and relates to the field of welding, in particular toa nickel-based alloy welding flux with the excellent crack resistance. The welding flux aims to solve the technical problem that existing large-area surfacing nickel-based alloy micro cracks are difficult to control. The welding flux components are composed of CaF2, SiO2, Al2O3, CaO, NaF, MgO, Cr2O3 and an alloy agent, and the welding strip components are composed of C, Si, Mn, S, P, Ni, Cr, Nb, Cu, Al, Ti, Co, Mo and the balance iron. According to the provided welding flux used in cooperation with strip surfacing nickel-based alloy welding strip with the excellent crack resistance, the ability of surfacing metal to resist high-temperature ductility-dip cracks can be greatly improved, wherein the welding flux and a welding strip are used in a matched mode, for the welding flux, powder andalloy with low impurity elements such as S and P are selected as welding flux preparation raw materials, the content of alloying elements Nb, Ti, Mn, Mo and the like is adjusted so that deposited metal crystal crack and DDC sensitivity can be reduced, and the method is used for a multi-layer welding process.