The new assumption that a photon cannot be split is made in the Monte Carlo simulation for optical scattering response function is made，which eliminates the uncertainly in arbitrarily choosing the threshold of photon death. A hyperbolic method is proposed to simulate the Gaussian beam used in optical coherence tomography systems where curved sample interfaces are encountered. Comparison between the calculated OCT pictures of a microscope slide (flat interface) and a cornea (curved interface) with the corresponding experimental ones indicates the effectiveness and the relative advantage of our new simulation method.