Beam spreading near the sea surface environment is measured in the experiment by dynamically-tested atmospheric beam system. Comparative analyses are then conducted between the experimental data and the theoretical value of both the marine power spectrum and the traditional Kolmogorov power spectrum. Results show that the measured ampltude fluctuation of beam spreading is lager than those of the marine power spectrum and Kolmogorov power spectrum, and the theoritical value of beam spreading for marine power spectrum is small when the measured inner scale is used to calculate. The beam spreading model for the marine power spectrum is closer to the experimental data than that for the Kolmogorov power spectrum with the increase of the refractive index structure constant of atmosphere. The difference between the theoretical value of the marine power spectrum and the experimental data is about 0.1~1.5 cm at 1 km link distance and 0.1~1.8 km at 2 km link distance. Both the relative errors are within 0.1% ~11.4%.