Considering the quantum confinement effect in silicon nanoparticles, the effect of the mean silicon nanoparticle size on optical band gap, optical transition oscillator strength, and the temperature dependence of the band gap and optical radiation, a model is introduced to analyze the photoluminescence (PL) of silicon-nanostructure thin film with a certain size distribution of silicon nanoparticles. Where Gaussian function as well as log-normal function is considered for size distribution of silicon nanoparticles. The results show that there will be blue shifts of the PL peak energy decreasing with mean size and size dispersion. As the temperature increases, the PL peak exists red shifts accompanied by decreasing of light intensity. The comparative analysis of the simulation results and experimental data of PL implies shows that our model can well explain the PL in silicon nanostructure thin film in different temperatures.