A simple, accurate, sensitive, precise & reproducible UV spectroscopic method has been developed for the standardization of emodin in pure form and in indifferent extracts of medicinal plant. Emodin was estimated at 437 nm in methanol medium. Beer’s law was obeyed in the concentration range of 10- 100 μg/ml (r2= 0.973). The method was tested and validated for various parameters according to the ICH (International Conference on Harmonization) guidelines. Emodin content in extracts of various plant parts carried out at 3max. The detection and quantification limits were found to be0.41μg/ml and1.25μg/ml, respectively. The present study deals with stability of Emodin, studied for futher using spectral reagents like NaOMe,NaOAc,AlCl3 for their spectral shifts studied by UV-VIS spectroscopic and Infrared spectral method. Emodin content in extracts of various plant parts of Cassia auriculata L was found using same method. The results demonstrated that the procedure is accurate, precise and reproducible being simple, cheap and less time consuming, and hence can be suitably applied for the estimation of emodin in different dosage forms.