Abstract: Using the inlet methanol electronically controlled injection mode, methanol is mixed combustion in the agricultural single cylinder diesel engine, the injection pressure and temperature of methanol will change the amount of methanol injected in each cycle, which directly affects the methanol mixing ratio of the single cylinder diesel engine. Using the experimental method, under the conditions of different injection pressure and methanol temperature, the variation law of methanol injector flow with methanol injection pulse width was measured, the flow characteristics were analyzed, and a modified MAP of methanol circulating injection volume was proposed. The results showed that the methanol injector was in the invalid injection stage when the pulse width was 0-0.5 ms. The circulating flow rate of 0.5-1.5 ms increased nonlinearly with the increase of pulse width. When the pulse width was greater than 1.5 ms, the circulating flow rate increased linearly with the increase of pulse width. The circulating flow increased with the increase of the injection pressure and temperature of methanol, in the stage of 1.5-10 ms, the circulating flow increased by 4.8% on average every time the injection pressure increased by 25 kPa, and the circulating flow increased by 3.2% on average every time the methanol temperature increased by 15 ℃. When the injection pressure and methanol temperature changed, the proposed modified MAP could effectively correct the methanol injection amount.