1. The solenoid valve attracts and overcomes the pressure of spring to drive the valve plug with the magnetic force produced from magnetic 　　coil upon energization, simple structure and cheap price, but could only realize open and close.
　　The electric valve drives valve stem through motor, then leads to drive the valve plug. It is divided into shutdown valve and regulating valve. The shutdown valve could only complete fully open and close, the regulating valve is to install positioner, stable the valve to one position through closed-cycle adjustment.
2.Switch form:
　　The solenoid drives through coil, could only open or close, but with short time for operation.
　　The electric valve is always driven with motor, the operation of open or close needs certain time, could be regulated.
3. Nature of operation
　　The solenoid valve always has low transmissibility coefficient and working pressure difference. For example, the transmissibility coefficient of caliber 25 solenoid valve is smaller than caliber 15 electric ball valve. The solenoid is driven through magnetic coil, is easily damaged by voltage surge. It could only complete open and close, just like a switch.
　　The electric valve is driven with motor, durable for voltage surge. The solenoid valve needs rapid open and close, is generally used to the machine with small flow and pressure. The electric valve’s opening could be controlled at status of open, close, half open and half close, could control the flow of media in the pipe, but solenoid valve fails to meet this demand.
The solenoid valve can be reset after power failure, but electric valve needs to install position restorating device.
4. Applied technology:
　　The solenoid valve is suitable for special demand, such as leakage, fluid media, with expensive price.
　　The electric valve is generally used to regulate, but has switching valve, such as fan coil terminal.