In　this　paper,　an　electronic　control　unit　(ECU)　used　in　vehicle-used　natural　gas　engine　is　developed　independently.　A　series　of　starting　tests　and　idle　speed　tests　are　done　with　refitted　JL465Q5　engine.　AVR　single　chip　is　adopted　as　the　core　controller.　Multiple　tablets　type　is　adopted　by　the　ECU.　Air　bypass　valve　opening　degree　is　controlled　by　step　motor　in　order　to　adjust　air　inlet　quantity　when　starting　and　idling.　Natural　gas　allowance　is　controlled　by　an　electronic　injector.　Experimental　monitoring　system　is　developed　as　an　interface　connecting　staff　and　single　chip.　Speed　acquisition　system　is　developed　to　record　starting　process　accurately　in　real　time.　The　tests　indicate　that,　more　concentrated　mixture　and　higher　cooling　water　temperature　are　beneficial　to　cold　start　for　natural　gas　engine.　Incremental　PID　control　algorithm　applied　to　idle　speed　with　closed-loop　control　for　natural　gas　engine　is　efficient　and　effective,　and　the　control　effect　is　better.　The　experiment　results　show　that　the　ECU　of　autonomous　development　and　the　speed　acquisition　system　are　practical　and　feasible.