Conceptual reciprocating friction wear testing machine was researched,the dynamic analysis of the reciprocating system which has a great influence on the testing process was performed，and the inertia force of this system was balanced by adding counter weight to improve the dynamic characteristics.The optimization effect of dynamic characteristics was verified by the multi-body dynamics analysis in ADAMS.The results show that the shaking force of the testing machine is reduced greatly and the shaking moment is also reduced after the inertia force of the reciprocating system is balancedTherefore the method to balance the inertia force by adding counter weight is feasible.