The invention discloses a measuring method for network nodes of an underwater wireless sensor and a device. The method comprises the steps of: carrying out the interconversion of an electric signal and an ultrasonic signal by utilizing an ultrasonic transducer so as to complete underwater ultrasonic communication; calculating the relative distance between the nodes and the device by utilizing thetransmission delay between node communication as well as the propagation velocity of ultrasound underwater; and collecting the underwater environmental data information from the position of the nodesby utilizing a sensor specially used in underwater detection. The device comprises a microcontroller, an FSK modulating and power amplifying module and a transducer which are connected in series; a hydrophone, a weak signal amplifier, an FSK demodulating chip and a microcontroller which are connected in series; a power management module is used for supplying power for a circuit and managing a power supply; and an external spreading interface module is used for connecting with a corresponding interface sensor and peripherals. The invention realizes the underwater sound communication function with low cost and low power consumption and the distance measuring function between the network nodes of the underwater wireless sensor.