Modern transportation is the lifeblood of national economy. The brake disc is one of the important parts to ensure the safe and reliable operation of high-speed train. However, the brake disc is at high speed, facing harsh service environment, prone to wear, crack, and other phenomena, resulting in the failure of the brake disc. In this experiment, 24CrNiMo alloy steel powder was used as cladding material. By changing the process parameters of laser cladding, single-channel and multi-layer cladding layers were prepared on steel plates. By means of stereomicroscop, Zeiss microscope, SEM, microhardness test, and tensile test, the influences of process parameters on the single-pass forming and the microstructure and mechanical properties of multi-pass cladding layer were analyzed and compared. The results show that with the increase of laser power, the fusion width increases while the residual height decreases. With the increase of scanning speed, the fusion width and residual height both decrease. With the increase of powder feeding speed, the fusion width and residual height both increase, but pores and cracks are easy to appear. The surface of the cladding layer is lath martensite, acicular ferrite and upper bainite. The microstructures near the matrix are coarse pearlite, ferrite, and granular bainite. When the scanning speed is too high, the hardness of the cladding layer fluctuates greatly and the distribution is not uniform. When the scanning speed is 340 mm/min, the tensile strength of the cladded layer is 1 110.22 MPa and the elongation is 10%, which reaches the standard of traditional steel casting. Reasonable control of cladding process parameters can achieve high hardness, high toughness, and other performance requirements, and can realize efficient additive manufacturing of brake discs for high-speed trains.