Abstract: As an imaging technique with low radiation dose and improved contrast, digital X-ray tomosynthesis is widely used in clinical diagnoses. Based on the superior capability of X-ray phase-contrast imaging(PCI) techniques for imaging low density materials, the combination of X-ray tomosynthesis and PCI could potentially provide higher efficiency in the detection of soft tissues. The goal of this work was to develop a fast and low-dose imaging method for phase-contrast tomosynthesis, called grating-based phase-contrast tomosynthesis(GPC-Tomo), which integrates tomosynthesis with a grating-based PCI technique. During data acquisition with the proposed fast GPC-Tomo, the grating scanning and sample rotation occur at the same time, which is different from the scheme used for conventional GPC-Tomo. Without the phase stepping(PS) technique to extract the differential phase-contrast image at each projection angle for the conventional GPC-Tomo, the data collected by the fast GPC-Tomo is incomplete. Here, we propose a novel reconstruction method called inner-focusing(IF) reconstruction for the proposed fast GPC-Tomo. In the reconstruction stage, measured X-ray intensities from neighboring projection angles that pass through the reconstructed point are utilized to compose a stepping period for signal extraction. The proposed fast GPC-Tomo technique was validated by real experiments. The results demonstrated that the reconstructed images acquired with the fast GPC-Tomo are better than those acquired with conventional GPC-Tomo, and with near-equivalence in radiation dose. Furthermore, since the proposed fast GPC-Tomo employs continuous rotation, its scanning time is much less than the stop-and-go motion of the conventional GPC-Tomo.