Chaos synchronization using semiconductor lasers achieves high-speed physical-layer key distribution, but the chaos synchronization time of lasers limits the rate of key distribution. Consequently, the factors affecting the chaos resynchronization time in an open-loop injection-locked synchronization system of the vertical-cavity surface-emitting laser (VCSEL) have been numerically studied. Moreover, the experimental results demonstrate that the chaos resynchronization time can be reduced in three ways: increasing the bias current of the laser and the differential gain coefficient, or reducing the photon and carrier lifetime to shorten the relaxation oscillation period; reducing the linewidth enhancement factor that can reduce the complexity of laser chaos; and increasing the injection intensity and reducing the frequency detuning, which can achieve strong injection locking. Based on chaos synchronization, the results have theoretical reference significance for improving the key distribution rate.