In order to improve the accuracy of fault diagnosis for dynamic system

and reduce the diagnosis influence from operating environment

a new fusion method in multiple classifier system based on dynamic weight is proposed.The new approach dynamic assigns weights to base classifiers according to their classification accuracy and decision support value.Bigger weights are assigned to more reliable decision output

and the weights of unreliable outputs are close to zero.In this sense

a subsystem is used to make final decision instead of system.Experimental results demonstrate that the new fusion method can get good fault diagnosis performance

and it can get higher accuracy than single classifier and some common used fusion methods.