The present invention discloses a heat preserving wall concrete aggregate grain diameter selecting and pouring method, which comprises the following steps: a, preparing a concrete with separable aggregate grain diameters, wherein, the aggregate grain diameters of the concrete adopt subsection continue preparation, the pebble with grain diameter of 5 to 10 mm is 30 to 35% of the total amount of the pebble, and the pebble with grain diameter of 10 to 30 mm is 65 to 70% of the total amount of the pebble; b, conveying the concrete with separable aggregate grain diameter to a pouring working surface by a set of concrete conveying equipment, separating the concrete by using a concrete aggregate grain diameter selecting and separating device, conveying the concrete with small grain diameter aggregate to a shuttering with small thickness and pouring the concrete to a protection wall, and conveying the concrete with big grain diameter aggregate to a shuttering with large thickness and pouring the concrete to a shear wall, and the two pouring processes are carried out at the same time; c, vibrating the concrete at the two sides to guarantee that the concrete is compact. The invention has convenient construction, easy operation, low cost and excellent pouring effect, is suitable for the construction of the home building and office building in various forms in the town, and has good society and economic benefits.