The invention provides an energy-saving and emission-reducing system for vehicles, vessels and buses. According to the system, when a traveling vehicle meets the conditions such as a red traffic light and the like and is required to stop and wait for longer time, an engine under the control of the system is in a halt mode and does not consume fuel any more, and when the traffic light turns to green and the vehicle can travel, the engine under the control of the system can automatically restore the working state. Therefore, the system has the advantages as follows: firstly, the fuel consumption of the vehicle in the waiting state can be reduced; secondly, the pollution of the urban environment due to tail gas emitted by the vehicle can be reduced.