Accidents of chemical dangerous goods (CDG) are the typical public emergencies. In recent years, the accident rate has shown a clear upward trend. In order to prevent or reduce accidents, this paper carries out the study on the public management capability of CDG accidents. By taking Jinan City as an example, the fuzzy analytic hierarchy process (AHP) was used to evaluate the public management capacity of CDG accidents. Then, the ArcGIS-based public management capability decision support system of chemical dangerous goods was constructed, to simulate the ammonia leakage accident and analyse the emergency evacuation module. The research results show that: 75.3% of the experts believe that the public management capacity of CDG accidents in Jinan City is in a good or general state, and more attention has been paid to the crisis prevention and early warning ability before the accident; the system estimates the evacuation area, the evacuation personnel (38,792 people) and the best route for evacuation (1,536.84195458m long) after instantaneous rupture of 15t ammonia transport vehicle. This study has certain practical significance for preventing and reducing the casualties of people and property caused by CDG accidents.