The invention relates to an emergency load rejection method for a deepwater autonomous underwater vehicle (AUV), which comprises a master control system and an emergency load rejection module adopting an active load rejection mode. When the emergency load rejection module runs, load rejection time is set, and the load rejection time is up but the triggering signal of the master control system is not received, a load rejection function can be started to throw out a heavy object to force the AUV to float upwards, and then, a reset signal is sent out by the master control system, and timing is started again; when the master control system normally runs, the signals can be continuously sent out to reset the emergency load rejection module to stop load rejection; when an abnormal condition is detected by the master control system, a load rejection command can be directly sent out to force the AUV to carry out rejecting load and floating upwards; when a fault is generated on the master control system per se, a procedure or a circuit is caused to run in faults, and at the time, the emergency load rejection module is capable of automatically judging; the reset signal cannot be received after a timing period is reached, thereby, the load rejection command is sent out, thus, the AUV can be forced to carry out rejecting the load and floating upwards, thereby, the running safety of the AUV is ensured to a greater degree. The emergency load rejection method for the deepwater AUV is capable of ensuring that the AUV to emerge from the water under any abnormal conditions so as to avoid the loss condition of the AUV happening.