The invention discloses a multi-frequency switchable underwater construction cleaning and maintenance device. A control panel is connected with a controller for realizing two-way signal transmission; a signal output end of the controller is connected with control signal input ends of a first multi-line analog switch group, a second multi-line analog switch group and a third multi-line analog switch group respectively; output ends of at least two ultrasonic signal generators are respectively and selectively connected with an isolation driving module through the first multi-line analog switch group; an output end of the isolation driving module is connected with an ultrasonic power amplifier; an output end of the ultrasonic power amplifier is connected with an impedance matching network; input ends of at least two tuning inductors are respectively and selectively connected with the impedance matching network through the second multi-line analog switch group, and output ends of the tuning inductors are respectively and selectively connected with a multi-frequency ultrasonic transducer through the third multi-line analog switch group. The multi-frequency switchable underwater construction cleaning and maintenance device disclosed by the invention can realize ultrasonic vibration cleaning with at least two frequencies, fully peel off dirt on an underwater construction, improve a cleaning effect, effectively reduce the cost and improve the working efficiency.