Abstract: The balance valve has the advantages of good load holding function and pipeline burst or serious leakage to prevent the uncontrolled occurrence of moving load. However, when the rescue truck mounted drilling rig is used for the lifting system, due to the large weight of the supporting drilling tools of the rescue drilling rig, the reasonable matching of the balance system is a design problem. In this paper, the scheme of balanced speed regulation system plus forced oil replenishment system is proposed. The balanced speed regulation system realizes the stable and controllable lowering speed. Forced oil replenishment can effectively prevent air suction and improve the safety and service life of the feeding system. The overbalanced hydraulic system is analyzed theoretically, and then the system dynamic model is established. Based on this model, the pressure and flow characteristics of the overbalance system are dynamically analyzed, the influence of the parameters of the balance valve on the dynamic characteristics of the feed and pull-out system is emphatically analyzed, and the parameter matching method of the overbalance system is proposed. The theoretical analysis results are verified by bench test. The results show that the weight of drilling tools has a great impact on the output of the conventional balance system. Setting the over balance speed regulation system in the feed and pull-out system of the drilling rig and reasonably matching the over balance parameters can realize the output stability of the feed and pull-out system and avoid the problems of air suction and out of control of speed.