The invention discloses a power distribution network investment effect preceding-evaluation method based on a type-2 fuzzy theory. The method comprises: firstly, proceeding from practical projects of power distribution network reconstruction, selecting key indexes, establishing a power distribution network investment effect evaluation index system; then, according to the type-2 fuzzy theory, performing type-2 fuzzification processing on each index in the index system, that is, giving the type-2 fuzzy marking section of each key index, so as to calculate to obtain quantitative marking sections of distribution network construction status level of each urban bureau; furthermore, according to difference of the status level marking sections, performing vertical classification on each city, the classification respectively being corresponding to cities in different levels; and finally, based on effective planned investment amount reported by distribution network projects of electric power bureau of each city, calculating distribution network investment effect ratio of the cities, and analyzing and comparing investment effect of distribution network construction reconstruction projects of different cities in a same classification.