The thesis investigates the correlation between a company’s bargaining power and cost of equity by adopting Compustat non-financial firms during 1990 to 2014 as the original study sample. Empirical results show that bargaining power is significantly and negatively correlated to the cost of equity, revealing that companies with stronger bargaining power uses their advantages to improve transaction condition to stabilize earning volatility, and further to cut down cost of equity capital. Further, this study finds that bargaining power is also significantly and negatively correlated to market beta. Finally, the influences of bargaining power on cost of equity and systematic risk are investigated by different levels of firm size and market competition. The results show that the negative relationship between bargaining power and cost of equity and market beta are stronger for small-sized companies.