Parallel gas-electric hybrid systems gains broad application prospects in low-carbon ships benefiting from few emissions and dynamic performance. However, due to uncertain delays of multiple actuators during mode transition, the shaft speed along the power drive tends to fluctuate violently. In this paper, a cascaded Internal Mode Controller (IMC) consisting of filters with explicit nominal delay is proposed to improve speed tracking performance and eliminate the effect of delay. A dynamic model of the marine driveline is built, then, the cascade IMC is designed according to the driveline mechanism in which the clutch serves as the separating component . The cascade IMC includes an anti-saturation compensator, a two-stage tracking controller and a two-stage anti-interference controller. Finally, the small-gain theorem is derived to ensure robust stability conditions, taking the upper bound of the uncertain delays into consideration. The results of simulation and dynamometer test show that the cascaded IMC has good robustness to deal with uncertain delays, significantly reduces shaft jerk and obtains smooth mode transition.