By analyzing the characteristics of the communication channel in the bi-directional digital wireless endoscopy system, this paper presents all efficient ARQ scheme with dynamically adaptive packet length for the system with high data rate and ultra-short communication distance．Furthermore, this paper also presents a novel method which is capable of dynamically adapting packet length so that it can approach the optimum value for varying channel bit error rates．The simulation results and the way to realize the ARQ scheme aye given out in this paper．