Abstract: By using a strong light-absorbing surface layer and front-surface illumination with a low power He-Ne laser (6mW), photoacoustic measurements of the thermal effusivities of materials have been made, based on the photoacoustic theory, derived in this paper of condensed matter with a strong light-absorbing surface layer. This method can eliminate the stray light, give full play to the power of the light irradiation, and improve the signal to noise ratio. The experimental results are in good agreement with values given in the literature.