Aluminium phosphide should be reduced in recent years, until the substitute was developed and employed. A low PH3 concentration circulating fumigation by sealing grain surface with polystyrene foam plate was developed combined with food grade inert powder flour mixture (LPCFSP). The performance of LPCFSP was studied in No. 30 large ware house with No. 28 large ware house as control, which was fumigated with conventional method. LPCFSP could reduce 37.5% aluminium phosphide to 20 kg. The half-life of PH3 was doubled to 19 days and the period of PH3 above 150 mL/m3 was more than 28 days in No. 30. The insect killing rate of high-resistance pest cryptolestes ferrugineus was 100% in No. 30, which was considerably higher than that in No. 28 with a killing rate of 45%~65%. The study proved that LPCFSP can be recommended for the high performance in aluminium phosphide reducing and insect killing.