An improved ph3.2 A-PAGE method was utilized to analyze the gliadin banding pattern with eight sampling methods 22 populations of 5 species in Agropyron Gaertn. The results showed that simpson indexes increased along with the seed number in the bulked seed samples increasing. The whole gliadin banding patterns obviously changed among different seed samples.On the whole average, the most gliadin number was 28.24 when seed number were 18, and the least was 18.38 when bulked seed samples were 3 seeds. CV% of the gliadin number was 13.21 meanwhile, the gliadin banding patterns were relatively uniform when bulked seed samples surpassed 12 (included 12) seeds. Therefore, bulked seed samples above 12 could be chosen to represent whole populations based on the genetic diversity of gliadin.