Human-AI synergy-driven cross-regional capital flows serve as a new quality engine for breaking regional segmentation barriers in the construction of the national unified market and activating the optimal allocation of capital factors nationwide. It is also a key leapfrog mechanism for intelligent technology to empower the building of a Chinese-style modern economic system. Based on panel data of Chinese A-share listed companies from 2009 to 2023, this paper empirically investigates the impact of human-AI synergy on enterprises' cross-regional investment. The study finds that human-AI synergy significantly promotes enterprises' cross-regional investment, and this promoting effect exhibits a long-term nature that gradually amplifies over time. This effect is more pronounced in private enterprises, enterprises with high market position, and low-technology enterprises. Human-AI synergy facilitates cross-regional investment primarily by reducing internal and external transaction costs, enhancing enterprises' market competitive position, and alleviating their perceived uncertainty. Further analysis reveals that cross-regional investment significantly boosts the high-quality development of parent companies. Importantly, the promoting effect of human-AI synergy on cross-regional investment does not stem from the crowding-out of the local market.