The invention discloses a microelectromechanical ultrasonic probe. The microelectromechanical ultrasonic probe comprises a silicon substrate (1), wherein an oxide layer (2) is arranged on the upper surface of the silicon substrate (1), a plurality of cavities (3) are formed in the upper surface of the oxide layer (2), the plurality of cavities (3) are arranged in rows and lines, a vibrating film (4) is bonded to the upper surface of the oxide layer (2), an isolation layer (5) is arranged on the upper surface of the vibrating film (4), sunken isolation grooves (6) are formed in the surrounding edge of the isolation layer (5) and in the isolation layer (5), the isolation grooves (6) penetrate through the isolation layer (5) and the vibrating film (4), then the bottoms of the grooves are formed in the oxide layer (2), and upper electrodes (7) are arranged in positions, which are over against the central positions of the cavities (3), of the upper surface of the isolation layer (5). The microelectromechanical ultrasonic probe has the advantages of reasonable design, novel structure, small size, wide frequency band, high sensitivity, low noise and good stability.