The invention discloses an under-point projection device suitable for mine measuring. The device comprises an external carrier, a spherical segment carrier and a fixing plate, wherein a laser transmitter is vertically installed on the cross section circle center of the spherical segment carrier, a circular level and a balancing device are symmetrically installed at the two ends of the laser transmitter respectively, the top of the laser transmitter is parallel to the cross section of the spherical segment, the external carrier is connected with the spherical segment through a traction rope, crossed wires are carved in the periphery of a lens of the laser transmitter, when liquid in the device is static, the laser transmitter is switched off when a laser is vertically projected to a point of a top plate, and aligning and leveling are conducted taking the circle center of the top of the laser transmitter as a reference point. The device has the advantages that the production cost is low,the carrying is convenient, projection can be conducted below the point, so that a point which needs under-point aligning is converted into a point on which above-point aligning is conducted taking the top circle center of the laser transmitter as the reference point, and the aligning efficiency and accuracy are improved.