The invention provides a speed-limiting protecting device for a self-elevating platform lifting system. The speed-limiting protecting device comprises a lifting motor, a planetary speed reducing box, a brake, a speed-limiting unit and a control unit. The lifting motor is used for driving a lifting platform, the lifting motor is fixed to the planetary speed reducing box, the brake is installed on a high speed shaft of the planetary speed reducing box, the speed-limiting unit reads the real-time rotating speed of the lifting motor and transmits the corresponding signal to the control unit, and speed-limiting protection on the lifting motor is conducted through the control unit. According to the speed-limiting protecting device for the self-elevating platform lifting system, duplicate protection on the lifting motor when the motor is overspeed is realized through the arrangement of the components such as a rotating speed encoder, an overspeed switch, a frequency conversion cabinet coding unit and an overspeed relay, and operation safety of the platform lifting is protected to the most extent, so that accuracy and flexibility of the speed-limiting protecting device for the self-elevating platform lifting system are improved.