Abstract：Test information is often incomplete in the fault diagnosis process of equipment. And simultaneous fault diagnosis process is more difficult at the same time. In response to this situation, in this paper the current method of fault diagnosis with incomplete test information and of simultaneous fault diagnosis is studied firstly. Then the paper defines incomplete fault diagnosis decision system to describe incomplete test information. And it defines incomplete boundary rough entropy to measure the level of uncertainty in the system and assign the importance of each attribute. Meanwhile, the method to calculate frequency of attributes’ value under condition of incomplete is proposed. In order to diagnose simultaneous fault, the paper constructs the diagnosis model under DSmT framework. And proposes a new combination rule of interval-value evidence to overcome the shortcomings of previous method exist. Finally, the validity and applicability of the method is proved by two equipment fault diagnosis examples.