The feasibility of real-time monitoring on biological tissue laser thermal damage based on visible and near-infrared spectroscopy is investigated. Thermal damage experiment is carried out in fresh porcine livers with laser of 5 W, 808 nm. Visible and near-infrared spectra (330～1100 nm) are acquired in real time at distances of 4, 8, 12 mm from the damage center, and the diffused light intensity at 720 nm (R d 720)is chosen as the evaluation factor. Results show that R d 720 increases quickly with the increasing of tissue temperature in the initial stage of heating. The smaller the distance between the spectral measurement point and damage center is, the faster R d 720 will increase. After reaching the effective damage, temperature continues to rise while R d 720 tends to be stable if keeping heating. After the heating is stopped, the tissue temperature gradually returns to room temperature, while R d 720 decreases slightly and remains almost a constant which is far higher than its initial value. It can be found that the visible and near-infrared scattering intensity of biological tissue can be used as an important parameter to real-time monitoring laser thermal damage.