The invention discloses a paddy rice heatproof breed ear period selecting method; when a sample breed grows to a 3-leaf-1-heart period, the samples are transplanted to a transplanting barrel, and respectively placed in land and a greenhouse; high temperature processing is carried out for the sample breed in the greenhouse, and the sample is moved to the land, and forms a matched group with the sample in the land until maturation; finally a heatproof coefficient is calculated according to a high temperature processing maturing rate / matched maturing rate, and hear resistance conditions of the different sample breeds are analyzed. The ambient temperature in the high temperature processing period can be increased by artificial heating, so selection pressure is increased, thus more accurately selecting heatproof material; in addition, shading treatment is carried out in a booting stage, thus ensuring a consistent paddy rice florescence; stems of paddy rice of different florescence are cut off before high temperature processing, thus ensuring consistent processing period.