The invention discloses an offshore operating personnel drowning monitoring system, which comprises a drowning monitoring module, a positioning module, a communication module and a control module, wherein the drowning monitoring module is used for monitoring related information of offshore operating personnel; the positioning module is used for monitoring the positioning information of the offshore operating personnel; the communication module is used for transmitting the information to a back-end system; and the control module is electrically connected to the drowning monitoring module, the positioning module and the communication module, and is used for judging whether the related information which is monitored by the drowning monitoring module is normal or not and/or for analyzing and comparing the related information which is monitored by the drowning monitoring module with original related information saved in the control module, so as to judge whether the related information is normal or not, and when the related information is abnormal, drowning alarm information is transmitted by virtue of the communication module, and the related information monitored by the drowning monitoring module and the positioning module is transmitted to the back-end system. The monitoring system provided by the invention is timely in alarm, accurate in positioning and capable of avoiding misoperations.