所谓贸易收支改善就是顺差扩大，或者逆差减小。

至于这种说法的根源可以追溯到重商主义盛行的时期~（详见http://en.wikipedia.org/wiki/Mercantilism）

下面这段总结自Michael Pettis的Great Rebalancing：

Mercantilism countries put into place policies, including import restraints and export subsidies, aimed at generating a positive balance of trade in which the country exports more than it imports. The defense of mercantilism is that it permits the practitioner to generate net inflows of assets that can be accumulated for a number of purposes: the ability to wage war(historically), defend currency stability, maintain payments of foreign loans and obligations, and guarantee access to imported commodities in times of financial distress.

Thomas Mun's England's Treasure by Foreign Trade (1664): The accumulation of specie would lead to greater availability of capital domestically, and so would lower costs of capital for businesses. The lower cost of capital would promote domestic economic growth.

谢谢你！有理有据 令人信服
每次都是你热心的帮我

你提的问题也都很值得思考，一起加油！

谢谢！一起加油！

在一起！