Abstract: Total RNA was isolated from Dendrobium displaying different status by using the methods of TRIZOL Regent, Guanidine Thiocyanate, Tris-H3BO4, and improved RNA isolation. The quality of total RNA was analyzed through gel electrophoresis and UV spectrometer. The results indicated that the RNA isolated by the improved RNA isolation method showed clear bands of 28 S rRNA and 18 S rRNA，and the value of OD260nm/OD280 nmwas close to 2.0. RNA isolated by the other three methods degraded and dispersed in some degrees.RNA isolated by the improved RNA isolation method could be reverse to cDNA .The cDNA was used for RAPD amplifying and two clear bands could be observed in agarose gel. These results demonstrate that the quality and purity of the RNA obtained by the improved RNA isolation method can meet the demands of molecular biology experiment.