In order to study the rules of crowd evacuation in medical buildings and analyze the influence of group evacuation mode on crowd evacuation, the Pathfinder evacuation software was used to investigate evacuation rules in a 5-story medical building. The simulation results show that with the increase of the maximum distance (d) between group members, the crowd evacuation time and the crowd congestion time showed a decreasing trend. Especially when the maximum distance is changed from 1.0m to 1.5m, the evacuation time drops most obviously. When the maximum distance exceeds 2m, the evacuation time of the crowd does not change much. In the case of d=0.5m and d=1.0m, the crowd congestion in the stairwell is more serious than that in the plane. With the increase of the proportion of patients, the crowd evacuation time shows an increasing trend. No matter how large the proportion of patients is, 70% of the pedestrian congestion time is between 45s and 65s. It is concluded that the adverse effects of group movement should be taken into account in the evacuation system design and evacuation guidance of medical buildings.