Abstract: In lower layer of Ⅴoil group of Shuanghe oilfield, each water flooding development index reflects much difference of water injection exploitation effect, according to the fuzzy and uncertainty, fuzzy comprehensive evaluation has been chosen to study on comprehensive evaluation of water injection effectiveness. Of all, ten important and representative evaluation indexes has been selected. Weight determination using the AHP, single factor evaluation vector in judgment matrix has been determinated by the optimization of ridge form distribution function. Comprehensive evaluation results suggest the water injection development effectiviness is within "good" evaluation scope, just coinside actual data. The method used in this paper is simple, practical, and the evaluation result is feasibly and reliable, which has guiding role for the oilfield further exploitation. Meanwhile, this method can also provide some enlightenment for similar reservoir for exploitation.