The crusher is one of the key components of the slurry balance shield machine， which generally uses hydraulic motors to drive the roller mechanism to crush rocks. Its hydraulic system is a closed system. The impact load on the crusher can sometimes cause it to momentarily stop， and the pressure on the low-pressure side of the hydraulic motor drops sharply to negative pressure for a short period of time， causing the hydraulic motor to become empty and resulting in motor damage. This article focuses on the problems existing in the hydraulic system of crushers， analyzes the reasons for the pressure suction on the low-pressure side of the hydraulic motor when the crusher suddenly stops under impact load conditions， and proposes an optimization scheme to increase the oil replenishment accumulator. Through simulation analysis and experimental verification of the scheme， it is proposed to adopt an optimized solution of adding a 4L accumulator at each outlet of the left and right drive motors of the crusher， in order to solve the problem of damage caused by pressure suction of the hydraulic motor of the crusher.