In this paper, the stability of multi-variable fractional order nonlinear dynamic system is investigated. We propose the definition of generalized Mittag-Leffler stability with multi-variable and introduce the fractional Lyapunov direct method with multi-variable. Meanwhile, a novel approach is suggested to study generalized Mittag-Leffler stability in multi-variable fractional order nonlinear dynamic systems. An interesting multi-variable fractional order Lotka-Volterra predator-prey model is used to illustrate the proposed method and its effectiveness. (C) 2013 Elsevier Ltd. All rights reserved.