The optical properties of random Sb-SiN films in which Sb nano-particles are randomly dispersed were studied. Results show that the random Sb-SiN films possess high transmittance and low optical absorption. Additionally, some optical nonlinear phenomena of the random Sb-SiN films have been observed. Based on the special optical properties of random Sb-SiN films, they can be applied in many fields, for example, optical storage and optical microscopy. When the random Sb-SiN film was prepared close to a phase-change-recording layer, it decreases the threshold of input power for recording and speeds up the phase transition of recording media, and also improves the resolving power of readout system. On the other hand, while the random Sb-SiN films were deposited on the slide glass used in far-field optical microscopy, it obviously improves the resolving power of optical microscope and reduces the value of resolution limit to less than half of the value calculated by the expression given by Lord Rayleigh.