Liquid Droplet Radiator (LDR) system is regarded as a quite promising waste heat rejection system for aerospace engineering.A comprehensive review on the state-of-the-art of LDR system was carried out.The thermal design considerations of crucial components such as working fluid,droplet generator and collector,intermediate heat exchanger,circulating pump and return pipe were reviewed.The state-of-the-art of existing mathematical models of radiation and evaporation characteristics of droplet layer from literatures were summarized.Furthermore,thermal designs of three LDR systems were completed.The weight and required planform area between the rectangular and triangular LDR systems were respectively compared and the evaporation models for calculating the mass loss were evaluated.Based on the review,some prospective studies of LDR system were put forward in this paper.