1． The State Key Laboratory of Fluid Pow er Transm ission and Control，Zhejiang University，Hangzhou 310027，China；
2．Oil Production Technology Research Institute，Shengli Oilfield Corporation，Dongying 257000，China
Abstract Special designs are used tO fit the usage of hydraulic pum ping unit on ocean platform ．It is completely controlled by hydraulic circuit，and a close loop hydraulic circuit with several hydraulic accum ulators is used to save energy． Experimental results show that the design of hydraulic control system is correct and it works properly．
