This study analyzes the correlation between economic growth and development of financial system by using panel data from 9 Pearl River Delta cities over the period 1990-2012. We employ three different regression models which include cross sectional estimator, first differenced GMM estimator and system GMM estimators, and obtain a positive correlation between the two factors mentioned above. The result of this study was contradicted with the existing researches in China which suggest financial development will slow economic growth because the banking sectors lack liberation of market. The cause of the contradiction is that most of the past literatures is just concerned about the data before China had been accepted in the World Trade Organization (WTO) in 2001, but this research also include the data after 2001 when China began the financial reform. Furthermore, this paper also give strong evidence to support that it is helpful to increase economic growth with the reform in financial system after China joined to the WTO. Empirical tests are done to examine the reliability and sensitivity of the research. The results confirm previous work and ensure the significant positive correlation between financial development and economic growth in the Pearl River Delta. Keywords: Financial development, Economic growth, GMM