The reconstruction expressions of the laser temporal-spatial distribution retrieved from temperature field of the heated surface have been obtained. Becuase the characteristic Abelian kernel function exists in integral representations, the integrations are ill-conditioned and the solutions are instable. In order to solve the ill-conditioned problems, the generalized functions theory and regular transformation method are utilized to reconstruct the integral functions. The reconstruction algorithm for laser intensity temporal-spatial distribution from measured temperature distribution on the target-surface is obtained. The sensitivity of the retrieved intensities to measured temperature error is analyzed. The developed algorithms is verified by numerical simulation. The relations of reconstructed intensity errors varying wth target thickness and irradiated time are gained by numerical simulation. The results show that the retrieved intensity distributions accord with those in the initial model for two kinds of boundary conditions on the back surface. The algorithm can be applied to monitor laser parameters on the target surface under intense laser irradiation.