Water-recovery is very useful for ease water shortages in our country cities. But this engineering’s investment is huge and capital pay back is very long. This type of environmental engineering depends on the government investment primarily, but now financial only from the government already cannot satisfy needs. In order to reduce the government's financial burden, we should expand more financial channels. Therefore, this kind of project financing decision is becoming more and more important. This paper puts forward a method considering policymakers experience combine with objective date. This Information entropy theory model can order according to approach degree in order to select the best scheme, which can provide a kind of subjective and objective for project financing decision combined with decision making method, making the decision more reasonable.