This article analyzes how economic growth, economic population, budget deficit, disposable income per capita and currency affect the theoretical scale of a country’s trade with traditional economic perspective. The study found that China owns the strongest trade competitiveness in the “BRICS” five countries, the second is Russia. India, Brazil and South Africa are respectively after that. From the point of view of trade competitiveness, though economic population, economic growth, and fiscal deficit on China trade scale role better than the rest of the four countries, but the disposable income per capita in South Africa have the greatest positive affect of foreign trade scale, and almost no impact to China. In addition, the exchange rate appreciation for China's foreign trade scale of most negative effects. In the short term, therefore, China could continue to maintain strong trade competitiveness, but not necessarily if in the long run.