The invention provides a water-logging-preventive life-saving underwater working cap which comprises a cap top and a cap body. A spring floating cover is arranged on the cap top, an air incoming platform is arranged on the spring floating cover, a plug is arranged at the lower end of the cap top, an extensible tube winding disc is arranged on the cap body, a breathing hose is mounted on the extensible tube winding disc, one end of the breathing hose serves as an air inlet and is fixed on the air incoming platform, an air incoming one-way valve is arranged on the air inlet, the other end of thebreathing hose serves as an expiration port, and an expiration one-way valve and a mouth-nose cover are arranged on the expiration port. The working cap can protect head safety, and is supportive ofunderwater breathing when a user of the working cap falls into water, thereby improving safety of working close to water.