Abstract: Taking E141A constant deceleration braking system in JKMD 4.5×4 mine hoist as research object, working principle of the constant deceleration braking system was analyzed. A simulation model of the constant deceleration braking system was built and reliability of the simulation model was verified by theoretical calculation. Typical faults such as spring stiffness decrease, friction factor of brake shoe decrease and brake leakage were simulated. The simulation results show that performance degradation of main components cannot immediately cause failure of the braking system, but can cause system performance degradation such as braking system pressure degradation, braker clearance smaller or bigger, etc. The braking system performance degradation with a certain degree will cause faults such as unsatisfactory braking deceleration, no braker clearance, too large braker clearance, too long idle motion time, etc.