Abstract: As a simple and new calculation method of reliability index,Rosenblueth method dosen’t need to know the probability distribution of all kinds of st ate variable.Only by the averages and variance of state variable we can get the reliability index of soil slopes,and the calculate accuracy meet precision demands.Rosenblueth method dosen’t need to calculate much data and is easily handed by computer.The fundamental principle of Rosenblueth method have been presented in detail. We use the FORTRAN language to write the calculator program and prove its advantage by comparison.It’s a method that is worthy of applicating in the engineering practice.