Abstract: A single-pass 10-layer high-strength steel wall part was manufactured by CMT(cold metal transfer) arc additive manufacturing, and the influences of wire feeding speed, welding speed and interlayer cooling time on the width, height and forming accuracy of the formed parts were discussed. The variation of microstructure and tensile properties under different process parameters was also studied. The results show that the highest forming accuracy of the sample is achieved under the conditions of wire feeding speed 3.5 m/min, welding speed 300 mm/min and interlayer cooling time 60 s. With the increase of wire feeding speed, the forming accuracy and height of the formed piece first increase and then decrease, while the width gradually increases. The transverse and longitudinal tensile strength of the test sample decrease gradually. The width of the formed part decreases with the increase of welding speed and interlayer cooling time, while the tensile strength of the sample in transverse and longitudinal directions is opposite. Compared with the vertical tensile strength, the tensile strength and elongation after fracture of the transverse specimen are larger, and the number of dimples in the transverse specimen is relatively large, but the size is small. Both of them are tough fracture. Increasing the wire feeding speed increases the number of needle ferrite in the central region of the formed piece and reduces the content of granular bainite. Increasing the welding speed or interlayer cooling time decreases the number of needle ferrite in the central region of the formed piece and increases the content of granular bainite.