In order to solve the practical problem that it is difficult to find water and control water of most screen completed horizontal wells in offshore oilfield due to across flow between screen tube and reservoir, annulus chemical packer（ACP）and plugging agent are researched to form the technology of stepwise and intelligent WSO based on the technology of electronically controlled valves for water control.Experimental studies show that the pressure of ACP is more than 2 MPa/m in the external annular pressure simulation device of original size screen tube,the gel plugging rate reached 95.79 % in high permeable tube by location injection of electronically controlled valves.The phenomenon of "profile inversion" appears in high and low permeability tube after plugging, which makes the diversion volume of low permeability tube with low fluid production increase from 9 % to 80 %, surpassing the production of high permeability tube.This indicates that low permeability tube has been well utilizedand the stepwise and intelligent WSO has a good WSO effect.