The underline challenge of low thermal conductivity which is responsible for high centerline temperature in Uranium-dioxide (UO2) nuclear plant fuel type associated with the current generation of commercial reactors remains a huge concern to the nuclear power industry. Although, researchers in the nuclear industry have proposed uranium mononitride (UN) as a promising candidate for accident tolerant fuel and Generation-IV nuclear reactor fuels, unfortunately, there is still a lack of clear understanding of the point defects influence on the thermal conductivity of UN. This paper applies the reverse-NEMD method to study the effect of point defects on phonon thermal conductivity in UN perfect crystal. Experimental and simulation relevant literatures were reviewed to analyze the influence of defects on the phonon thermal conductivity of UN. The thermal conductivity of uranium mononitride increases quickly with the temperature and the phonon contribution decreases with an increase in vacancies concentration. Uranium vacancy has a detrimental effect on the phonon thermal conductivity of UN at lower vacancy concentration. Results from this research would help with the understanding and application of UN in nuclear engineering.