This paper analyzes the role of patent quality on companies' investment value and its impact mechanism. Firstly, this study uses Patent Authorization Rate, Average Inventor Number and Technology Scope to measure patent quality, and then puts forward the theoretical hypothesis. Empirically, this study finds that patent quality can promote firms' investment value, and the effect on high-tech or board companies is significantly positive. Further study finds that the effect of patent quality is significantly positive on state-owned enterprises and that the higher the patent protection level is, the greater the promotion effect is. The impact mechanism is that, patent quality first influences gross profit rate, then improves business performance, and finally promotes firms' investment value.