Pk301 is one of the important equipments of 4×105 t/a polypropylene project in Pucheng Clean Energy Chemical Limited Company. In view of Pk301 units shut down abnormally in the process of recycling recovery of the low pressure propylene gas to the high pressure propylene scrubber. The reasons that caused Pk301 shut down which are abnormal vibration of cylinder block, the higher temperature in the secondary outlet and lower pressure in the first inlet were analyzed. The corresponding solutions were presented.