In recent years, using external mechanical energy to solve environmental pollution problems has gradually become a promising strategy, such as piezoelectric catalysis and piezoelectric photocatalysis. In this paper, a series of HKUST-1/g-C3N4 composite materials were successfully synthesized by the combination of g-C3N4 with S-vacancy and porous HKUST-1 semiconductor. Under visible light irradiation and ultrasonic action, the catalytic activity of HKUST-1/g-C3N4 on RhB degradation was investigated. When the mass ratio of HKUST-1 to g-C3N4 is 1:0.3 during the process of piezoelectric photocatalysis, the as-prepared HKUST-1/g-C3N4 composite had the best RhB degradation performance up to 94.42%, which is about 2.83 times that of visible light and 3.56 times that of ultrasonic waves. According to the result of the trapping experiment, the process of piezo-photocatalytic reaction could produce the number of reactive oxygen species (ROS), and the hydroxyl radical (•OH) was crucial in the breakdown of pollutants. Display omitted •HKUST-1/g-C3N4 with the piezo-photocatalytic property was synthesized.•The catalytic mechanism under ultrasound and UV–visible light was revealed.•Superior piezo-photocatalytic activity has been obtained by HKUST-1/g-C3N4.