Simulation method is widely used in system reliability analysis and not affected by the dimension of state function. But traditional simulation method will need large number of samples to obtain more accurate results when the failure probability of each component is quite low. Survival signature theory divides the system reliability into probability structure and system structure, which makes the calculation process easier and clearer. However, the assumption that components are independently and identically distributed (𝑖𝑑𝑑) is very idealistic which hinders the further application of this method. This paper presents two methods to calculate system reliability based on survival signature theory system with independent but nonidentical components and dependent components. This paper mainly discuss the complex calculation of nonidentical components and the exchangeability assumption of related components.