Abstract: Wheat Blue Dwarf is one of the main disease on winter wheat in Northwestern China. A 1.2kb fragment was amplified by phytoplasmas universal primers in total DNA sample extracted from diseased wheat with dark green leaves and red dwarf symptom by Nested-PCR. The result indicated molecularly that the pathogen of Wheat Blue Dwarf disease was phytoplasma. The different symptoms (dark green dwarf and red dwarf) were all caused by phytoplasmas. Nested-PCR could be as a rapid, exact technique for detecting the pathogens from wheat leaves, insect vectors and weed host.