Based on single metal droplet deposition behavior research, and established the three-dimensional numerical calculation model of lap forming entity parts, explores the molten metal drop in little space, large temperature gradient in the sedimentary forming under the environment of melt flow, spreading, coagulation mechanism, reveals the typical cross section on lap forming, the main characteristics of droplet deposition factors and the influence law of forming between morphology, internal quality, obtained the optimum process window, for subsequent complex metal parts of molten drops flow deposits forming provides technical support and reference.