The invention discloses a power grid N-1 safety economic dispatching and optimizing method taking transmission operation flexible space into consideration. The method mainly includes the steps: 1) acquiring power grid basic data; 2) building a transmission line fault short-time capacity-increase flexible model; 3) building a connecting line adjusting flexible model; 4) building an N-1 safety economic dispatching model considering transmission operation flexible space; 5) optimizing a power grid according to the N-1 safety economic dispatching model considering the transmission operation flexible space. According to the method, when fault short-time capacity-increase is considered and the transmission operation flexible space is adjusted by the connecting line, the optimization space of setoutput is improved, and an operation feasible region of a power grid is widened. According to the optimizing method taking transmission operation flexible space into consideration, the wind power acceptance capability of the power grid is further improved on the premise of reducing operation cost.