The invention relates to a reliability analysis method of an electric power system, specifically a wind power grid-connection system operational reliability evaluation method considering uncertainty factors, and solves the problems of incomplete consideration, long time consumption, slow convergence, resource occupation and incapability of realizing real-time prediction and evaluation of the existing method. A scheme comprises the processes as follows: I, uncertainty factor modeling: A, load comprehensive uncertainty; B, a conventional power generator comprehensive time varying operation model; C, comprehensive time varying operation modeling; D, wind power plant operational reliability modeling; and II, a Markov chain model: E, a Markov process and a Markov chain; F, a wind power Markov chain model; and G a wind power reliability evaluation index. The beneficial effects are achieved as follows: by performing quantitative analysis and comparison on the degree of influence of load fluctuation, element state and wind power output on the operational state and reliability level, the reliability level at the current moment can be evaluated, and the state probability at the future momentcan be quickly predicted, so that planning, overhaul, operation optimization and dispatching of the electric power system can be guided, thereby overcoming the shortcomings of the conventional evaluation method.