Using a balanced panel of manufacturing firms from China between 2007 and 2013, we estimate that being connected to a high-speed rail (HSR) system leads to 9.5% reduction in local firms’ input inventory spending. The effect is stronger for downstream industries and private enterprises. A back-of-envelope calculation suggests that each dollar of HSR investment reduces input inventory stock by 12 cents, which is significantly larger than the effects found in previous studies based on highway or road investment. Declines in transportation and communication cost, as well as agglomeration effect, are identified as plausible mechanisms. Our findings reveal a micro channel through which improved transport infrastructure brings about economic gains, and contribute to the cost-benefit assessment of HSR investment.