Take the neutral pen sleeve as an example, the plastic mould with 1 mode 48 cavities was designed. Firstly, the non-equilibrium gating system was designed preliminarily and optimally, the BGV values of it were calculated and compared, the optimum design dimension was determined. Then, two kinds of filling analysis models were established. The results show that the optimal design can reduce the time gap between the firstly filling and lastly filling , the filling pressure by 20MPa.Finally, according to the optimization design of the gating system for the structure of the mold design and production experiments, the experiment proved that this sub-grouping optimization design for the sub-runner, it shortens the processing cycle of the mould, guarantees the quality of the plastic parts, realizes the high efficiency production, and provides a feasible reference for optimizing the filling of multi-cavity mould.