This study explores the relationship between cost of capital and stock returns. Using weighted average cost of capital as investment signals, I buy low weighted average cost of capital stocks and sell high weighted average cost of capital stocks at the same time to construct a zero investment portfolio. Then, I test whether the returns of the portfolio significantly different from zero. The results shows that weighted average cost of capital has ability to differentiate between goods stocks and bad stocks. But the portfolio can earns significant returns only when the market is up-market. And the average return of the portfolio can’t better than market returns.