The 35% TC4+65% Ni60 single-pass Ni-based laser cladding layer was prepared on the surface of TC4 substrate by the TruDisk4002 coaxial powder feeding fiber laser， and there were no cracks within the coating. The finite element model of the coating was established by the ABAQUS software. The simulation results of temperature field show that the molten pool has an obvious "coma tail" phenomenon， which is consistent with the motion characteristics of the actual laser heat source. The maximum temperature of the molten pool is about 3200 ℃. The temperature gradient is large at the front of the laser heat source， however that at the back end of the heat source is small. The shape characteristics of the molten pool and the coating are basically the same， and the size error is less than 5%. According to the residual stress field distribution of the coating， the stress concentration in the edge area and the bonding zone of the cladding layer is relatively large， where it is easy to form cracks. The cracks on both sides of the cladding layer are mainly related to the distribution characteristics of Gaussian heat source， and the cracks in the bonding zone are mainly caused by the difference of the thermo-physical properties of the cladding materials. The experimental results show that there occur obvious crack defects in both the edge area and the bonding zone of the coating， which is consistent with the finite element calculation results.