Previous studies and current clinical practices have applied laser therapy without effective feedback and guidance, resulting in highly variable outcomes. A method of integrating laser therapy and sweptsource optical coherence tomography (OCT) is presented to implement real-time monitoring of tissue thermal interaction process. OCT interference spectral signals are continuously acquired in M-mode fashion without translating the skin sample, yielding depth-resolved measurement of the same axial line as a function of time during laser exposure. Thermal injury evolution is monitored quantitatively in real time through analysis of the measured complex reflectivity, in which variations in the magnitude and changes in the phase of the complex reflectivity are extracted to detect the overall aggregate changes of the scattering centers and measure the displacement in the axial direction. Meanwhile, attenuation coefficient is obtained to determine the extent of tissue thermal damage based on OCT scattering model. The experiment results indicate that thermal coagulation and necrosis occurs under irradiation of a certain laser power with the time lasting. During the process, the thermal injury boundary propagates downward monotonically and the optical attenuation coefficient nonlinearly increases. The demonstrated correspondence with microscopy and histologically determined injury depth and magnitude suggests that these techniques may enable precise monitoring and mapping of laser thermal therapy.