Abstract: Affected by various factors,the oilfield output pos- sesses the characteristics of macroscopical trend with cer- tainty and microcosmic fluctuation with randomness, while an accurate forecast of oilfield output is of great im- portance for development.Therefore,a grey-Markov forecast model based on the fundamental principles of Grey System and Markov Chain is established,which is mutually complementary in their respective superiority and inferiority and able to bring out more reliable and ra tional forecasting.Application indicates this method is of higher accuracy,and can he applied in the oilfields with certain change trend and big random fluctuation.