With the advancement in stroke rehabilitation, the application of upper limb rehabilitation robots for patient recovery is becoming increasingly popular. However, traditional rehabilitation robots face challenges such as complex control systems, high costs, and heavy structures, which hinder their widespread use in homes and small medical facilities. This paper introduces an innovative upper limb rehabilitation robot with a five-bar structure characterized by its flexible joint parallel configuration and user-friendly operation. This study conducts an in-depth analysis of the robot’s kinematic properties and singular poses. Moreover, through the OpenSim simulation platform combined with Myoelectric Sensors data, we precisely investigate the dynamic changes in the activation levels of certain muscles and joint angles during rehabilitation. Experimental validations demonstrate that the robot can effectively promote moderate activation of key muscles, with all joint angles moving smoothly within their range of motion, indicating that the proposed device can provide effective rehabilitation training.