Abstract: When applying wire arc additive manufacturing technology to repair damaged molds, poor forming problems such as gaps, dents and excessive accumulation may occur at the edges, which lead to the uneven thicknesses in the clading layer and impact the precision of the additive manufactured parts.In order to aovid these defects, a variable thickness layer slicing algorithm is proposed, which mainly consists of model pre-processing, determination of welding parameters, correction of slicing thickness, and completion of the additive manufacturing process. By adjusting the overlap rate during the cladding process, precise control of the thickness variation of the formed part can be achieved, which help to improve the forming precision and decrease the defects as mentioned above. Finally, this variable layer thickness slicing algorithm was used for pyramid structure models, and cladding experiments were conducted. The results showed that the calculated filling path could fully ensure the full filling of the specified layer, and there was little difference in height, length and width between the cladded part and the calculated one. Hence, the forming precision is satisfactory to the industrial requirements on condition that the heat accumulation is low.