This paper is to valuate the main factors that should be considered by TNCS (transnational corporations) when they want to choose a country as emerging market. The main factors include the advantages of TNCS as well as the key conditions of the country. This paper takes the Wal-Mart for example, as the Wal-Mart is the representative transnational corporation, which chose China as emerging market years ago, and grows to an efficient scale now. This paper firstly uses the Eclectic Theory to analyze the advantages of the Wal-Mart, and secondly uses the Porter diamond Model to analyze environment in China. The conclusion of report will get ideas for TNCS to evaluate whether a country is qualified for an emerging market more efficiently.