Shedao pit-vipers (Gloydius shedaoensis) on Snake Island in the Liaoning Province,China,are among the most imperiled species in China.The isolated and unique populations are crucial in the recovery of this endangered species by providing a way for conservation and management.Research based on the ecological simulation tools can evaluate alternative mitigation strategies in terms of their benefits to the populations,which are vital for informed decision-making.In this paper,using the program VORTEX 9.42,we developed a population viability analysis (PVA) for the Shedao pit-viper to:(1) address the extinction likelihood of the population; (2) simulate population dynamics under various environment events,and (3) evaluate the efficacy of current protection and management strategies.Overall,we found the population to be susceptible to the factors of catastrophic events,mortality and environment capacity.The population is recovering slowly at present on account of improvement of habitat and greater food availability.Under the current conditions,the probability of extinction in 100 years is approximately zero.These data coincide with the evidence that the wild population may be arriving at K.Our results strengthen the view that protection and management can create a pronounced effect on populations of this endangered species.