To understand the diffusion and distribution of sulfuryl fluoride in wheat, rice and soybean piles, experiments were carried out in 6 warehouses to compare and analyze the diffusion speed, uniformity, and attenuation speed of fumigant gas in different grain piles. Data were collected in the process of fumigation. Experiment results show that the diffusion rate of sulfuryl fluoride gas in different grains is quickest in the soybean pile, followed by the rice pile and wheat pile: the soybean pile can achieve uniform gas in its warehouse as soon as 8 hours after fumigation. The average gas concentration half-life is longest in the soybean pile, shortest in the rice pile with the wheat pile stands in the middle: the fumigation concentration of 5.0~12.7 g/m3 can safeguard an insect-free environment for 6 months.