To solve the problem of the inert dust repellent application on the grain bulk surface in grain store houses with transverse ventilation, the characteristics of pervasion and distribution of inert dust aerosol, in the diagonal airflow before the film was covered, were analyzed by collecting samples of the powder from different points on grain surface and previously embedding insect cages in the heap of grain. The results showed that there was no significant statistical difference among the amount of settlement powder collected from different parts of the surface of the grain heap, which indicated that diagonal airflow did not affect inert dust evenly distributed on the grain bulk surface, and can be used to protect the part tend to occur pest in the grain bulk after being covered with film. A good protective effect against pest was achieved that mortality rate of Cryptolestes turcicus reached 100%, mortality rate of Sitophilus zeamais was 95% and the density of Sitophilus zeamais in warehouse decreased 85%.