Abstract: Build-up of fluid in producers generally is up to4Mpa in Zhangdian oilfield,a high oil-to-gas ratio oil-field brought into production in2000.Too high or low a casing head pressure has a great impact on fluid produc-tion from oil layers.A rational casing head pressure range of producers is presented in this paper:2Mpa is the rational pressure in wells with relatively shallow dy-namic fluid level and high production rate,while1Mpa in well with relatively low production rate and deep dy-namic fluid level.