The environmental worthiness and reliability are important quality characteristics of materiel，which directly determine the materiel function would exert normally or not. The connotation of time，environment，and capability in their definition were analysed. The relationship and difference of their definition were contrasted. The status of measurements for these two quality characteristics was introduced. The connotation，development and primary methods of environmental test and reliability test were explained. Thereby the relation between environmental worthiness and reliability was presented.
