Abstract: In this article,a simulating method of computer which is used in the stochustic vibration of tracked skidder is presented.The tracked skidder is simplified into a system of vibration which has three degrees of freedom of skidder-seat. Employ the J-50 type skidder made in China as a example.the field test result compares favourably with the result of simulating calculation on the DPS8 type computer. In addition,make use of the method of this calculation,the authors researched the construction parameters influence on riding comfort of the tracked skidder and suggested some opinions to improve the riding comfort of the J-50 type skidder.