Aiming at the problem about the poor stability of broekn belt fixed throttle buffer brake system, the traditional broken belt brake hydraulic system was optimized. A new type of variable throttle buffer brake belt hydraulic system was proposed.The AMESim simulation model of the optimized hydraulic system for broken belt brake was established.The smooth brake performance of the optimized system was verified by simulation. The influence of different initial brake speed and total brake mass on brake displacement, brake speed and displacementbrake force was analyzed. The research results show that:when the initial brake speed is increased or the total brake mass is increased, the broken belt braking displacement remains unchanged, all within 1.0 m.The influence of brake speed and brake mass on the belt brake characteristics is consistent. The braking displacement range of hydraulic cylinder with constant brake force is extended with the increase of initial brake speed or total brake mass.