Does the outdoor emergency stop button of a gas station need to be grounded?

No need. The outdoor emergency stop button of the gas station should be connected in series to the control loop. Connect the live wire to one of the contacts of the emergency stop switch, and then use the live wire to connect the normally closed contact of the emergency stop switch to the starting end of the control loop. No grounding is required. Gas stations refer to refill stations that serve cars and other motor vehicles and retail gasoline and engine oil. They generally add fuel oil, lubricants, etc.