The uncertainty problem of geotechnical engineering is one of the hotspots of research in recent years. Based on the reliability analysis of slope and the introduction of the principle of unscented transformation, the analysis methods and implementation steps of slope reliability based on unscented transformation are given. With the help of the examples of the homogeneous slope and the layered slope in the existing research, the rationality and applicability of slope reliability analysis method based on unscented transformation are discussed. The results show that the reliability analysis of slope based on the principle of unscented transformation does not depend on the distribution types of variables, and the unscented transformation is convenient in application and efficient in calculation. When the slope with higher reliability is analyzed, a large relative error is caused because the value of failure probability is small, therefore, the methods should be chosen carefully. But the slope with lower reliability (higher failure probability) which is more concerned in engineering, the method of slope reliability analysis based on unscented transformation has good applicability. At the same time, the relative error of this method is less than 5% when compared with the Monte Carlo method and the error fluctuation caused by the change of variable correlation coefficient is small.