The invention provides a method for evaluating operational risk of wind power farms in combination with weather and wind speed, comprising the following steps of: a, determining outage probability of equipment components under the current weather within an evaluation cycle; b, constructing a time sequence through an ARMA model and performing matrix transformation, thereby obtaining a wind speed sequence of each wind power farm; c, obtaining a system state according to the outage probability of the current weather, and performing sampling through a non-sequential Monte Carlo method; d, adding 1 to number of sampling, obtaining wind speed of each wind power farm at the current time, and calculating output of each wind power farm; e, according to output of each wind power farm, screening out a load bus meeting a preset condition, and corresponding load shedding value of the load bus, accumulating the load shedding value, and taking the accumulated value as minimum loss load quantity of the system; f, according to the minimum loss load quantity, calculating a risk indicator; g, when risk indicator variance is less than precision each time, returning back to the step d; and otherwise, outputting the risk indicator. By implementation of the method and the system provided by the invention, accuracy and reliability of evaluation of operational risk of the wind power farms can be improved, and evaluation result can be more scientific and rational, and has extensibility.