The macro-micropulse laser with broadband and circular polarization can effectively excite the sodium atoms in the mesosphere, which can offer more return photons for the wave-front sensing of the adaptive optics. Based on the two-level Bloch equation, considering the distribution of laser intensity under the different models for atmosphere turbulence in the mesosphere, the number of return photons for sodium laser beacons is calculated under the three models for atmospheric turbulence by the method of numerical simulation. Then, the scale of atmosphere coherent length is conjectured according to experience and the average value for the number of return photons is calculated. The average value is relatively close to the experimental values. Because the effects of the recoil, down-pumping and geomagnetic field can be neglected, the return photons can be computed by the effective absorption cross-section. However, this method leads to the smaller results of computation because there is no consideration of the influence of laser polarization, beam quality factor and intensity distribution on the probability of excited states.