To overcome the shortage of complex equipment, large volume, and high energy consumption in space capsule manufacturing, a novel sliding pressure Joule heat fuse additive manufacturing technique with reduced volume and low energy consumption was proposed. But the unreasonable process parameters may lead to the inferior consistency of the forming quality of single-channel multilayer in Joule heat additive manufacturing process, and it is difficult to reach the condition for forming thin-walled parts. Orthogonal experiments were designed to fabricate single-channel multilayer samples with varying numbers of layers, and their forming quality was evaluated. The influence of printing current, forming speed, and contact pressure on the forming quality of the single-channel multilayer was analyzed. The optimal process parameters were obtained and the quality characterization of the experiment results was conducted. Results show that the printing current has the most significant influence on the forming quality of the single-channel multilayer. Under the optimal process parameters, the forming section is well fused and the surface is continuously smooth. The surface roughness of a single-channel 3-layer sample is 0.16 μm, and the average Vickers hardness of cross section fusion zone is 317 HV, which lays a foundation for the subsequent use of Joule heat additive manufacturing technique to form thin-wall parts.