One of the most important biodiversity loss indicator is the complete extinction of fauna and flora. In order to prevent species extinction, factors that would impact on that should be identified. Populations of threatened Persain gazelle have been declining over the last half century. In this thesis, the main effective reasons in changing Gazelle population in Iran have been identified and each factors contribution is explained relatively, and an appropriate strategy for these factors is recommended claimed. The census statistics were collected from Iran's Environmental Protection Agency from 2007 to 2014 for 23 protected areas. Then, the growth rate of population was calculated by regression of Natural logarithm of population size (Log N) versus the census year. Variables like vegetation changes, number of farms, mines, villages, and isolation of areas using satellite imagery and geographic information system were extracted and information about variables as number of game guards, guard stations, water troughs, and the equipment were obtained by sending a questionnaire to the environmental departments around the country. Multivariate linear regression was applied to determine the effectiveness of each mentioned independent variable on the growth rate of population. The percentage of species in core area, and the total human land uses in the protected area buffer were recognized as the most important influencing variables. Appropriate strategies were suggested for maintaining the Persian gazelle populations in the region. Keywords: Persian Gazelle, Factors Affecting Extinction, Linear Regression Model, Growth Rate