The fault diagnosis problem of the TS fuzzy Causality Graph with the interval number is studied，and the fault interval based on the hyperellipsoid model is considered to be constrainedFirst，the TS fuzzy gate is set up，and a Hyperellipsoid model is established by DS theory to deal with the range of uncertainty parameters in the Causality Graph，and to solve the fault mechanism and polymorphism of the complex system Secondly，the Hyperellipsoid model is transformed into a unit Hyperellipsoid model，and the random number of the uniform distribution is produced in Hyperellipsoid model，and it is uniformly sampled，thus the probability of fault possibility interval which is more in line with the actual TS rule is obtained Finally，Matlab is used to carry out numerical simulation，which confirms the validity of the conclusion from the Hyperellipsoid model Therefore，the Hyperellipsoid model can effectively slow down the difficulty of obtaining accurate data in the Causality Graph，which is more reliable and practical than the range model in the Causal Graph