In recent years，appreciation of the RMB and the rising of labor cost have become a hot topic in international community and academia，and one of the foci is their negative impact on Chinese economy. In the circumstance of RMB appreciation and the rising of labor cost，the research on the relationship between RMB exchange rate，labor cost and the international competitiveness of Guangdong grain is significant to improving the trade of Guangdong grain and international competitiveness of Guangdong grain. First of all，the author analyzes the current situation of RMB exchange rate，labor cost and the international competitiveness of Guangdong grain. To study the relationship between RMB exchange rate，labor cost and the international competitiveness of Guangdong grain，the author builds a co-integration model and make the trade competition index of Guangdong grain as explained variable. The explanatory variables are RMB real effective exchange rate，labor cost and so on. The result shows that there is a significant negative correlation between RMB exchange rate，labor cost and the international competitiveness of Guangdong grain. In other words，the international competitiveness of Guangdong grain will decline while RMB exchange rate and labor cost rise. At last，the author put forwards some suggestions to improve the international competitiveness of Guangdong grain depending on the research result.