For the stability analysis of jointed rock slopes, the strength reduction method based on the Hoek-Brown failure criterion is studied. Failure of slope is progressive. The attenuation degree of each strength parameter is different during the destroy process; so the reduction factors are different in the strength reduction method. Thus, the determination of the correlation between different reduction factors and the definition of the comprehensive safety factor is worthy of investigation. From the softening and hardening regularities of geomaterial perspective, the correlation between the three reduction factors in Hoek-Brown criterion is deduced in this article, based on the attenuation law of rock mass strength parameters from peak strength to residual strength. The slope stability can be evaluated with a comprehensive safety factor defined by the ratio of the anti-slide force on the sliding surface before and after reduction. Numerical simulation model is established based on the Hoek-Brown failure criterion; and the safety factor of slope is calculated using the strength reduction method. It is concluded that the calculated results based on Hoek-Brown failure criterion are similar to those calculated by other methods. The resemblance of their output validates the suggested method. The method proposed can be used in the jointed rock mass engineering, providing reference for the rock mass slope stability analysis.