Aiming at the problem of positive flow hydraulic excavator walking deviation,an optimal sequence multi-attribute decision-making method for fault diagnosis based on T-S fault tree was proposed.The walking hydraulic system of positive flow hydraulic excavator was studied,and the causes of walking deviation were analyzed.Finally,the multi-attribute decision-making method of optimal fault diagnosis sequence based on T-S fault tree was applied to the walking deviation analysis of positive flow hydraulic excavator.The probability importance of each component of positive flow excavator walking hydraulic system was solved by T-S fault tree as an important basis for fault diagnosis sequencing,and the optimal diagnosis sequence was generated by multi-attribute decision-making method.It plays an important role in quickly and accurately locating the fault source of positive flow hydraulic excavator walking deviation with minimum cost.