With the spreading of Covid-19 and seeking for a drug that helps people around the world to cure this disease.In this article, we used a plant(Cassia fistula) which is rich in anthraquinone glycosides to control the causative agent. Anthraquinone was extracted from Cassia fistula pods using alcohol method.Antioxidant activity of the extracted anthraquinone was analysed by using hydrogen peroxide scavenging assay.The best inhibition assay was 70% at100mg/mlconcentration. The docking study introduced atheoretical explanation for an interaction between two types of anthraquinone glycosides (rhein and aloe-emodin) in Cassia fistula against the main protease (7BZ5) in SARS-COV-2 virus, which gave a good binding energy score as -5.36491489 and -5.48040009 for rhein and aloe-emodin, respectively.