Waterflooding oil reservoirs are prone to develop different degrees of water-consumption zones，which thereby reduces the effect of reservoir development. Therefore，it is of great significance to study the characterization，quantitative grading，and distribution characteristics of water-consumption zones for further potential exploration of waterflooding oil reservoirs. This paper first established the quantitative characterization indexes of water-consumption zones considering reservoir permeability，crude oil viscosity and water saturation. Then，a grading method was developed for water-consumption zones from the perspectives of technology（seepage capacity）and economy，and it was applied to actual blocks in an oilfield. It is found that as the viscosity of crude oil decreases，the high water-consumption zones and extreme water-consumption zones develops rapidly and the corresponding pseudo-water-consumption rate drops when they are formed；as the permeability declines，the economic high water-consumption zones disappear，and non-economic low water-consumption zones appear. The current extreme water-consumption zones in Unit Ng3-4，Area A of Shengli Oilfield are mainly distributed near water wells，with a small development area；non-economic high water-consumption zones surround the extreme water-consumption zones，with a medium development area；economic high water-consumption zones surround non-economic high water-consumption zones，with a large development area；economic low-water consumption zones are distributed in areas with low displacement efficiency and have a large development area.