An array of periodic slits, combined with classic grid two-dimensional gratings, can acquire a dual band-pass characteristic in radar and optical wave band. The concentrated distribution of stray light energy will severely restrict the applications of classic composite film structure in high precision detection and imaging. To solve this problem, a novel composite film structure is developed in this paper, which is composed of slit elements and annular gratings. A scalar diffractive model is built based on Fraunhofer diffractive theory through contrasting the diffractive properties of two kinds of composite film structures. The theoretical simulations and experimental results both prove that the annular composite film structure can suppress the stray light effectively, for its higher transmittance, lower ratio and more uniform distribution of stray light, and enhance the reliability of composite film structure in the practical optical applications.