本篇研究以公司治理為主，聚焦於所有權集中所造成的公司治理問題，探討中國股權分置改革對上市公司資訊不對稱與權益資金成本的影響。本研究以2001年至2011年間上海交易所與深圳交易所的上市公司進行實證分析。在股改與公司治理機制之部分，實證研究結果顯示，股改與權益資金成本呈正向關係。此外，股改後的控制股東持股比例下降者，其權益資金成本是上升的。在公司治理機制與資訊不對稱的部分，實證研究結果顯示，以每日價差作為應變數時，控制股東持股比例與股權分離度皆呈顯著負相關；以分析師預測之標準差作為應變數時，僅有股權分離度呈顯著負相關。;This research focuses on corporate governance issues resulting from ownership concentration and examines if the share structure reform in Chinese stock markets affects the relation between corporate governance, information asymmetry and cost of equity capital. The research sample includes listed firms of Shanghai and Shenzhen Stock Exchanges from 2001 to 2011. We first investigate the relation between share structure reform and the cost of equity capital and find that they are positively correlated. Then, we examine the relation among share structure reform, corporate governance and cost of equity capital and document that the cost of equity capital is positively correlated with the dummy variable of the controlling ownership after the reform. Finally, we explore if corporate governance affects cost of equity capital through the channel of information asymmetry. The empirical results show that when we use bid-ask spread as the dependent variable, the controlling ownership and deviation are both negatively associated with information asymmetry. In addition, when we use standard error of analysts’ forecasts as the dependent variable, only deviation is negatively correlated to information asymmetry.