It is important for China to have diversified FTA partner objectives in which the promotion of Sino-SACU FTA should be a priority.

Different from the existent summarizing papers on customs union,the author discusses the western viewpoints on the trade effect of customs unions from three logically connected aspects:first,the interest source of customs union;second,the reasons for the formation of customs union;and third,the determination of optimal external tariffs.

The Impact of EU s Eastern Enlargement on Trade Between China and the EU——Based on the Analysis of The Trade Effect of Customs Unions;