Today, medicinal plants are still the primary reservoir of new drugs. They are considered an essential source of raw material for the discovery of new molecules needed for the development of future remedies. Among these plants, we find Urtica dioica L., which belongs to the Urticaceae family. It is a perennial herbaceous plant commonly known as "nettle" it has been reported to have various pharmacological activities like antibacterial, antioxidant, analgesic, anti-inflammatory, antiviral, and anticancer effects. In the present work, we are interested in one hand, in valuing this plant which was harvested from the region of Meknes, by thermal and gravimetric analysis ATD/ATG to determine the loss of mass as a function of temperature. This phenomenon was confirmed by the calcination technique in a muffle furnace at different temperatures (110 degrees C and 300 degrees C, 600 degrees C). on the other hand, after the calcination of the plants, detection of the heavy metal content by an atomic absorption spectroscopy (AAS) technique was performed. The results obtained showed simultaneously high concentrations of Ca, K, Na, Li, and Cd and low concentrations of Pb, Ni, Cu, and Zn.