Abstract: This paper analyses the technology keys about diesel engine burning diesel oil/methanol bi-fuel. On the condition without changing the former diesel engine structure and parameter. The control mechanism for supplying methanol was designed. Whole condition control on supplying diesel oil/methanol bi-fuel was achieved. On the range of 22%～56% of inhaling methanol capacity, the test and research indicate that the diesel engine worked steadily, both power and economic function were raised, the temperature of exhausting gas dropped. Smoke of exhausting gas made a marked improvement and starting function good on common temperature.