Based on the analysis of the development of cross-border e-commerce in BRICS countries and the status quo of cross-border e-commerce trade between China and other BRICS countries, this paper makes a quantitative analysis of China's cross-border e-commerce exports to other BRICS countries and its influencing factors. Based on the classical expression of gravity model, this paper adjusts the model and constructs an extended gravity model with China's cross-border e-commerce exports to other BRICS countries as dependent variable, GDP of other BRICS countries, distance between China and the BRICS countries, population of importing countries, consumption gap, Internet penetration, logistics performance composite index of importing countries and cultural gap as independent variables. Based on the panel data of China, Russia, India, Brazil and South Africa for 8 years from 2010 to 2017, this paper finds that the GDP of importing countries, Internet penetration of importing countries, consumption gap, logistics performance composite index and population have a positive impact on China's cross-border e-commerce exports to other BRICS countries, while cultural gap and geographical distance have a negative impact on China's cross-border e-commerce exports to other BRICS countries.