The development of integrated quantum photonics requires a high efficient excitation and coupling of a single photon source with on-chip devices. In this paper, we show our results of modelling for high-Q photonic crystal cavity,
optimized for zero phonon line emission of NV-centers in nanodiamonds. Modelling was performed for the silicon nitride platform and obtained a quality factor equals to 6136 at 637 nm wavelength.