The present invention provides a rapid positioning device and method based on an underwater beacon array. The device comprises an array formed by a plurality of underwater beacons Ai and a photosensitive positioning device that can be loaded in multiple types of underwater roaming devices. LED lamp groups and microcontrollers are arranged in the underwater beacons Ai, the LED lamp groups arrangedin the underwater beacons Ai can emit light of different colors through the microprocessors, and color light is set according to placement positions of the underwater beacons. The photosensitive positioning device has a built-in microprocessor and a photosensitive sensor. The photosensitive positioning device converts optical signals received by the underwater beacons into digital signals, the digital signals are processed and are sent to a roaming device through a series port, and the roaming device obtains an underwater specific position of the roaming device. When the roaming device move tothe vicinity of the underwater beacons Ai, the photosensitive positioning device loaded in the roaming device receives certain LED light of the underwater beacon array, and therefore, the underwaterposition of the roaming device is quickly obtained.