The invention relates to a power system short-term risk determination method taking disaster factors into account and belongs to the field of power system reliability and risk analysis. The method comprises the steps: geographically dividing regions where disasters causing power system transmission line failure are distributed (disaster regions for short, e.g. regions of lightning strokes, ice disasters, bird hazards and the like); establishing a corresponding relationship between power transmission devices and the disaster regions according to positions of the power transmission devices of a power system and the geographical distribution of the disaster regions; calculating the conditional failure rate of the power transmission devices located in the disaster regions when the disasters occur through carrying out statistics on historical failure of the power transmission devices of the power system and reasons for the historical failure; determining the power outage risk of the power system in a future short term by using power system risk assessment techniques according to weather forecast information and the conditional failure rate of the power transmission devices. By using the method, potential power outage accidents of the power system under disaster weather are warned, and maintenance plans and operating modes for the power system are arranged reasonably, so that large-scale power outage accidents of the power system are prevented.