Abstract：
Critical properties are one of the most important properties for pure chemical substances.Since they are very difficult to determine by experiment especially for unstable substances,it is necessary to find some good evaluation methods.Now the scientific workers can evaluate them by Group contribution methods,some equations using other normal properties and some equations using the existed equation for other properties.In this paper these methods are described and compared espacially the methods on the base of rackett equation.
2000, Vol. 17 
