Since 1978, China government has spent a huge amount on public capital, including infrastructure, education, and R&D. It is important to know whether those expenditures on public capital have a positive impact on improving manufacturing firms’ productivity and thus reducing their production cost. In this study, we applied a data set with 1,371,726 sample points from the manufacturing sector of China from 1998 to 2006 with a traditional cost function to estimate the impact of public capital on firms’ production cost, with a firm-level fixed effect. Then we estimate the substitutability of public capital and private inputs. We found that both education and infrastructure have a significant impact on reducing production cost for manufacturing firms, while education expenditure has a larger effect. On the other hand, R&D expenditure has little effect on reducing production cost.