In order to make clear the rollover index used in rollover warning and anti-rollover control and the influence degree of rollover risk factors, CarSim is used to establish a nonlinear dynamics model for SUVs. Experimental design on fishhook rollover tests based on simulation method is conducted, and the experimental results are analyzed by mathematical statistics methods. The simulation results show that：tire load transfer rate index in the characterization of vehicle rollover has higher reliability；the relations among vehicle skidding, steering ability and rollover mainly depend on the road adhesion situation；the newly proposed rollover risk evaluation index suitable for vehicle complex input conditions is able to analyze the influence of rollover risk factors on rollover risk.