Laser-induced evolution of the coupling state in a perpendicular exchange-spring L10-FePt/FeNi bilayer film is studied via time-delayed magneto-optical polar Kerr loops. A transient strengthening process of the coupling is found to occur simultaneously with significant reduction of the hard-phase coercivity at ~50 ps after the ultrafast demagnetization. Analysis of the time-dependent magnetization components and the micromagnetic calculation demonstrate that this delayed coupling-strengthening phenomenon originates from the opposite laser-modulation effects respectively on the hard and soft magnetic phases, in which the laser-induced transient reduction of the magnetic anisotropy in FePt phase plays the most important role.