Piezo-phototronic effect is unique for effectively controlling semiconductor and photonic properties by strain-induced piezoelectric field. In this work, we theoretically explore piezo-phototronic effect on intersubband optical absorption of wurtzite-structured AlGaN/GaN quantum well by self-consistently solving eight-band kp Hamiltonian and Poisson equations. Intersubband transition is associated with the transition of two electronic states so it has longer wavelength due to lower transition energy. Strain can also effectively increase absorption wavelength in Al0.15Ga0.85N/GaN/Al0.05Ga0.95N quantum well by quantum Stark effect. For Al0.1Ga0.9N/GaN/Al0.05Ga0.95N quantum well, absorption wavelength decreases with increasing strain. Quantum efficiency can be sensitively controlled by strain. This study not only provides the theory models of piezo-phototronics of intersubband transition, but also offers the method for continuously controlling terahertz application by piezo-phototronic effect.