The invention discloses a building energy-saving concrete blending device. The building energy-saving concrete blending device comprises a bearing plate, the left side of the top of the bearing plateis provided with a slide groove, the two sides of the inner cavity of the slide groove are both movably connected with pulleys, the surfaces of the pulleys are sleeved with supporting columns, a blending box is fixedly connected to the tops of the supporting columns, and a motor is fixedly connected to the top of the blending box; and a first rotary shaft is arranged at the output end of the motor, the bottom of the first rotary shaft penetrates through and extends into the inner cavity of the blending box, and the two sides of the first rotary shafts are both fixedly connected with first stirring blades. Through mutual cooperation of the bearing plate, the first stirring blades, the first rotary shaft, second stirring blades, a second rotary shaft, a fixing rod, the blending box, the motor, a movable shaft, a moving rod, a movable box, the pulleys, the slide groove, the supporting columns, a moving plate, a limiting groove and an air cylinder, the building energy-saving concrete blending device can achieve the high-efficiency stirring effect on the concrete when being used, and thus the stirring efficiency of the concrete is higher.