At present,when studying the motion precision allocation of mechanical transmission system,only the cost factor is considered,and the influence of the system motion precision stability on the precision allocation is ignored.Therefore,a multi-objective optimization allocation method of mechanical system based on cost function and precision stability was proposed.The meta-action theory was introduced and a precision cost function model for meta-action unit was established,and the comprehensive complexity coefficient was used to represent the relationship between meta-action unit precision improvement and the cost.Based on the motion error transmission model of the mechanical transmission system,the stability analysis model for the motion precision of the mechanical system was established.With the comprehensive cost and the system motion accuracy stability of mechanical system as the goal,a multi-objective optimization allocation model for mechanical system motion precision was established.The fuzzy set method was used to analyze the Pareto non-dominated solution set and to determine the optimal solution.Finally,taking the motion precision allocation of the NC rotary worktable system as an example,the proposed multi-objective optimal distribution method was compared with the single objective optimization allocation method,and the effectiveness of the proposed method was verified.