Aiming at the problems such as the early damage accumulation of concrete structure, a detection and evaluation method for the damage of concrete specimens based on thermoelastic intensity modulation laser technique for excited narrow-band ultrasound is proposed in this paper. With the help of the finite element simulation method, the ultrasonic wave by laser excitation of nonlinear mesoscopic damage concrete model is obtained. The spectrum analysis of the displacement signal on the surface of the concrete model is carried out and the relative nonlinear coefficient is calculated. On this basis, the piezoelectric ultrasonic second harmonic system and the percussion resonance fundamental frequency detection system are built, and the exponential regression equation of the nonlinear coefficient β′ and the dynamic modulus of concrete Ed is established. The results show that the proposed method has the advantages of non-contact and high sensitivity, and can provide a strong basis for early damage assessment of concrete structures.