The invention discloses a disposable embedded water stop joint for constructional engineering drainage and a construction method thereof. The water stop joint comprises a connecting pipe, a positioning ring, a water stop step, a base, a connecting hole, an arc-shaped lower water stop step ring, reinforcing ribs, a water stop hole, a spherical screen mesh and an upper water stop ring and can be applicable to pipeline penetration and installation of cast-in-place floors of rest rooms, kitchens, balconies, terraces and the like of residential building houses, and the installing accuracy of the water stop joint can be well ensured and the installation quality problem of the water stop joint can be prevented by arranging the positioning ring. In addition, the disposable embedded water stop joint can effectively prevent seeped water produced in surrounding gaps of the water stop ring in the construction process from causing leakage by being provided with the arc-shaped lower water stop step ring and the water stop hole, and ensures backflow of the seeped water. The disposable embedded water stop joint also prevents the blockage effect on the water stop hole of concrete sand in the construction process by being provided with the spherical steel wire mesh, can ensure the effect playing of the water stop hole and improves a water stop effect.