In recent years, the haze is very serious, automotive urea main role is to play a catalytic role automobile exhaust, make poisonous gases into non-toxic gases, State 4 diesel vehicles have a special urea storage tanks, in row the time when the exhaust gas discharge urea solution. To reduce air pollution, the state now has to implement national IV emission standards, then what is called the State 4 emission standards? State 4 emission standard is the fourth stage of the national emission standards for motor vehicles, through better catalytic converters active layer, secondary air injection and a cooling device with exhaust gas recirculation systems, use of technology, control and reduce vehicle emissions of pollutants to the standard value or less. According to the plan, as early as in 2013, Beijing has been released in the State 4 emission standards, vehicle urea added that diesel exhaust emission standards can be achieved. Thus, the vehicle can be said urea heavy trucks, buses and other diesel vehicles to achieve the national IV emission standards essential products.