The invention relates to a method and a system for calculating a short-circuit ratio value of a direct current transmitting end power grid. The method comprises the steps that the maximum transmissionpower of the direct current transmitting end power grid is determined according to a direct-current actual operation requirement; the minimum short-circuit ratio of the direct current transmitting end power grid is obtained according to the maximum transmission power and a pre-determined relationship between the direct current transmitting end power grid short-circuit ratio and the maximum transmission power, wherein the relationship between the direct current transmitting end power grid short-circuit ratio and the maximum transmission power is obtained by calculation through a pre-determinedcalculation formula of the direct current transmitting end power grid rectifying station constant current control operation characteristic and the direct current transmitting end power grid short-circuit ratio. The minimum transmitting end short-circuit ratio value is determined based on the direct current maximum transmission power, so that the problem that the power grid short-circuit ratio values are different caused by different modes of the direct current transmitting end power grid and the receiving end power grid is solved, and the method can be widely applied to the calculation fieldof the direct current transmitting end power grid short-circuit ratio.