Low pressure plasma spraying (LPPS) is a plasma spraying process under vacuum or very low pressure,which prepares coatings with lower impurity content, higher density and higher bending strength compared to the coatings prepared by Air plasma spraying(APS). This paper reviewed the characteristics of APS such as high flame speed, high stability, high deposition efficiency and good controllability, introduced the many technological advantages of LPPS, including clean spraying environment, high speed and long flame flow, auto-preheat and electric cleaning. This paper also reviewed the application of LPPS in some functional coatings, such as thermal barrier coating, anti-cavitation erosion coating and plasma facing materials. Furthermore, this paper forecasted the development trend of LPPS, including enriching related theory, combining with other technologies, on-line process control and a much lower atmosphere pressure, and its further application in aviation , aerospace, electronic and many other fields.