The invention belongs to the technical field of blast furnace ironmaking, and discloses a blending effect computing method applicable to the blending operation of iron ore powder. The blending effect computing method comprises the following steps: 1, finding iron ore content P(A) in blended material by mathematically modeling the blending operation process of the iron ore powder; 2, determining that probability of iron ore discrete type random variable X valuing around E(X) is more than or equal to Po; 3, finding the percent of pass P of continuous type random variable normal distribution of the testing ingredient in the blended material; 4, obtaining a blending efficiency computational formula applied to managing the blending operation by setting [eta] to be equal to P/Po, wherein, when [eta] is equal to 1, the blending effect is the best, when [eta] is more than 1, the more the [eta], the better the blending effect is, and when [eta] is less than 1, the less the [eta], the poor the blending effect is. According to the blending effect computing method, influence factors to the production of blending stock piles in a stock ground are comprehensively taken into consideration, thus being more accurately accordant with actual situation of the blending effect of the modern stock ground blending operation.