Disclosed are an anti-spalling blocking bar for a large cross-section coal gallery excavation work surface and a supporting method. The anti-spalling blocking bar comprises a blocking bar (1) and a support bar (7). Both a top portion of the blocking bar and an end of the support bar are provided with screw holes (2). A steel peg (5) is provided on an outer side of a bottom portion of the blocking bar. Locking teeth (6) is provided on an inner side of a mid-upper portion of the blocking bar, and a locking catch (8) is provided on one end of the support bar. The blocking bar and support bar are secured, using the screw hole and a screw bolt, to a temporary support device. After removing coal, a tool is used to hammer the blocking bar so as to wedge the steel peg thereof into a coalface (13). The locking catch of the support bar is held within the locking teeth to support a coal heading. After use, the blocking bar and support bar can be retrieved and suspended, using a hanging device, from the temporary support device. The anti-spalling blocking bar offers the advantages of easy installation, good support, reusability, convenient storage, and the like. The invention reduces the probability of personnel injury caused by coal loosening and falling from the heading, shortens the time for establishing coal heading support, and enhances a safety index and an excavation speed of a large cross-section coal gallery excavation work surface.