The present disclosure provides a portable seafloor drill rig for a submersible for multi-point core drilling, including a power head, a reduction gear box, an emergency jettison device, a drilling tool, and a temperature and pressure-retaining device. a water supply connector and the power head are arrange on a top plate of the reduction gear box. An output shaft of the power head is connected to an input shaft of the reduction gear box, and an output shaft of the reduction gear box is provided with a central hole, which is in communication with a water inlet hole of the water supply connector. An output shaft of the reduction gear box is connected to the emergency jettison device, and the temperature and pressure-retaining device can perform temperature and pressure-retaining storage of the core drilled by the drilling tool.