The microstructure and stress of the laser cladding layer have a significant impact on crack control of the cladding layer. The microstructure and stress of the cladding layer are closely related to preheating temperature during the cladding process. The microstructure and stress distribution of the cladding layer under different preheating temperatures are analyzed . The results show that the higher the preheating temperature, the stronger is the element interaction between the cladding layer and matrix. At a preheating temperature of 100 ℃, the peak value of the transverse residual stress decreases. The peak value of the residual stress parallel to the scanning direction decreases from 594 MPa at room temperature to 442 MPa, and that perpendicular to the scanning direction decreases from 579 MPa at room temperature to 383 MPa. Besides, when the preheating temperature is 200 ℃, the stress reduction effect significantly reduced. When the preheating temperature is 300 ℃, the microstructure stress effect is greater than that of room temperature, resulting in a significant increase in residual stress level.