In this work, a dynamic model of a Single link flexible manipulator based on the assumed mode method is presented. The manipulator has been considered as a past few years in the study of flexible robot manipulators dynamics and control. Motivated by the need to improve their productivity, interest has grown in the Bernoulli-Euler beam subjected to finite rotation. A computer program including the proposed model has been used to simulate numerically the dynamic response of a manipulator under investigation. The validity of the proposed model has been verified through the comparison between the dynamic response of the manipulator based on the proposed model and that based on a Finite Element model. The proposed model has been used to investigate the contribution of the main mechanical design parameters (damping, and payload) as well as the open loop control torque profile on the performance of the manipulator under investigation.