Abstract: At present, the construction of national parks has just started in China. It is of great significance to know the size of other national parks in the world for developing China's national parks. We counted the number and area of national parks in eight countries—Canada, Russia, the United States, Brazil, South Africa, France, Japan and New Zealand, and compared the scale of different types of national parks with historical culture, species, ecosystem, natural landscape and the complex as the main protection objects. Among all 308 national parks studied, two-thirds of them cover an area between 100 km² and 2 500 km². The national parks with an area less than 100 km² were generally established for their special historical culture, attractive island landscape, or rare species with narrow distribution, while those with an area of more than 2 500 km² were mainly for the protection of tropical rain forest, desert, tundra or the comprehensive protection of multiple ecosystems. According to the statistical results and China's conservation goal for national parks, we suggest that a national park for the comprehensive protection should be more than 500 km², and a national park for protecting river and lakes, coastal or island ecosystems, or geological relics could be smaller, but not less than 100 km². As the number of national parks in China will increase in the future, it is important to constantly reflect and summarize experience from practice, and keep exploring appropriate area of national parks in China.