The invention discloses a building sand screening device capable of automatically screening sand. The building sand screening device comprises a first check ring, and a first fixing block is fixedly connected to the bottom of the left side of the first check ring. Through cooperative usage of the first check ring, the first fixing block, a transmission mechanism, a second motor, a second rotationdisc, a second fixing column, a third transmission rod, a first fixing rod, a leakage net, a second check ring, a second fixing rod, a transmission case, a first motor, a first rotation disc, a firstfixing column, a first transmission rod, a first sliding block, a second transmission rod, an abutting moving mechanism, a reset spring, a second sliding block, a fourth fixing rod, a discharging pipe, a fixing plate, a feeding bin, a third fixing rod, a second fixing block and a transmission belt, the problems that a screen of an existing screening device is prone to blockage, and consequently the screening effect is poor are solved. The building sand screening device capable of automatically screening sand has the advantage that blockage is not likely to happen, and a user can conveniently use the screening device.