Objective: to understand the relationship between loneliness, social support and mental health of empty nest elderly in Xining City, Qinghai Province. Methods: 415 empty nest elderly in four districts of Xining city were selected by random sampling. The relationship among loneliness, social support and mental health of empty nest elderly in Xining city was studied. Results: loneliness and mental health of empty nest elderly in Xining city were negatively correlated, and had a significant negative predictive effect on mental health; social support and mental health werepositively correlated, and had a significant positive predictive effect; social support and loneliness were negatively correlated, and had a significant negative predictive effect. The multiple regression equation of loneliness and social support to mental health of empty nest elderly in Xining is significant. Loneliness and social support can jointly explain 21.1% of the variance of mental health.