Monte Carlo (MC), is a more flexible yet rigorous approach, which is able to describe the photon migration in the biological tissue and determine the quantities of photons depicting the distribution of fluence rate within the illuminated tissue. In photoacoustic tomography, the photoacoustic signals are generated due to the light energy absorbed by absorbers in the tissue, in which the absorbed energy density is the product of absorption coefficient and optical fluence. As such it would be essential to study how deep the light can penetrate the tissues and how the deposit energy retention in the absorbers determines the deep-seated photoacoustic effect in the tissue. In this paper, we will use MC to conduct simulation tests to systematically explore the deep-seated photoacoustic effect at the different wavelength of illumination, different depths and different sizes.