Experiments were conducted in steel structure seed-store house in Beijing in summer to investigate temperature and relative humidity. In the test period, the maximum temperature outside is 36.6℃, the maximum average temperature of the air inside is 27.4℃, and the maximum average temperature of the seed is 25.8℃, the difference of the maximum air temperature between the outside and inside of the store house is 9.2℃, the difference between inside air and seed is 1.6℃; temperature of upper layer of seed is 0.5℃ higher than the lower one; the maximum relative humidity of seed is 62%, and this level can meet the condition of the seed store, such as corn, wheat; the difference of maximum temperature between both sides of the south wall is 20.4℃; and the maximum heat conduct of the north wall is 67.0 W/m², while the south one is 120.5 W/m². It indicates that the airtight capability of the store house is very good. Finally, the suggestions management and problems that need to be studied further are put forward.