Abstract: This paper reported the design of a combined cavity injection mold with four small injection components for a smallsize thermoplastic electric product. The structural characteristics of each component were firstly analyzed, and then an optimized non-natural balance gating system was designed for this combined cavity mold on the basis of filling analysis results using the Moldflow Insight software. Afterward,the gating system, molding parts, demolding system and its operation procedure, cooling systems and structurewere designed. The experimental results indicated that the design methodology developed by this work could provide guidance and solutions for the design of small-size combined cavity injection mold and lead to a significant improvement in product quality for injection-molded parts.