The multi-layer film pulse compression grating used in expanding and compressing laser pulse is composed of multi-layer dielectric film with high reflectance and relief gratings on its top. Based on the designed multi-layer film with high reflectance, the distribution of diffraction field of multi-layer pulse compression gratings is analyzed by Fourier modal theory and the expression of its diffraction efficiency is given on the condition of transverse electric field incidence at Littrow angle. With the merit function of the first order diffraction efficiency of multi-layer dielectric film gratings, the grating parameters, with which the first order diffraction efficiency is higher than 0.95, are discussed when materials of top layer are HfO2 and SiO2, respectively. The results show that a larger grating parameter range is got with HfO2 than SiO2. Optimized structure parameters of gratings are given and errors of grating fabrication and tolerances in use are discussed, which gives some theoretical guiding to the fabrication technics and applications.