According to the distributing characteristics of large fragments of ore in Pingguo bauxite mine,in consideration of the protection of grizzly and the saving of energy,a theoretical analysis of the adjusting control of main parameters of Model USG 5 crawled hydraulic rock breaker was made.The practice has proved that the mathematical model and the dependence curve defined in this paper are correct.This paper is of instructive importance to the correct use of rock breakers with this constructional configuration.