The Rosenblueth Method is a simple and practical calculation method of reliability index as the probabi- lity distribution of all kinds of state variables does not need to be known
and only by using the averages and variances of state variables can one get the reliability index of soil slope. In this paper an explicit expression about landslide load-increased factor is deduced. Using the expression as the status function of reliability analysis and the advantage of Rosenblueth Method
a method of calculating the reliability of slope is put forward.