Objective To investigate the immediate impact of changes in kinematic and dynamic characteristics before and after visual intervention on the gait of hemiplegic patients. Methods Thirty visually normal hemiplegic patients were recruited. Plane mirrors (0°), concave lenses (+150°, +450°) were selected to simulate normal vision, moderate myopia, and high myopia scenarios for straight line walking tests. The Qualisys three-dimensional (3D) motion capture system and Kistler 3D force platform were employed to collect kinematic and dynamic parameters of the patients, and the differences in related indicators before and after visual intervention were compared. Results Visual intervention affected the step length, walking speed, and joint angles of hemiplegic patients. Especially after acute vision changes, there was a significant difference in the stride length and ankle joint angles on the patient’s affected side. Under high myopia, the step length and step length symmetry were better than those under moderate myopia, but at the expense of gait speed. Visual intervention led to asymmetric trends in step the length symmetry and joint angle symmetry. There were very significant differences in center of pressure (COP) and COP symmetry between normal vision and high myopia. Conclusions Acute vision changes can significantly affect the gait of hemiplegic patients, especially when there is a notable decrease in walking speed and changes in ankle joint angles with high myopia, and an increase in walking speed with moderate myopia. Additionally, under all conditions of vision changes, the COP symmetry is reduced, indicating a higher risk of falls. During the rehabilitation process of hemiplegic patients, reasonable vision assessment and corresponding intervention measures are expected to improve walking ability and life quality of the patients.