Abstract: Coral reef ecosystem is one of the ecosystems with abundant biological resources and powerful ecological functions of our planet.It provides important ecosystem services for human production and livelihood.Based on the study of monitoring and pre-warning research of resources and environment carrying capacity, the present paper developed a monitoring and pre-warning indicators system for evaluation of the ecological carrying capacity status of coral reefs, and delineated the evaluation grades and evaluation criteria for the ecological carrying capacity status of coral reefs.This study took the Xisha coral reef ecological monitoring zone as a case study to research and evaluate the ecological carrying capacity status and changing trends of the Xisha coral reef ecosystems, and further investigated the main causes of the degradation of the Xisha coral reef ecosystem.Finally this study proposed countermeasures and suggestions to reverse the degradation trend of the Xisha coral reef ecosystem and improve its ecological carrying capacity.