Periwinkle herb with the scientific name (Catharanthus roseus) is one of the most important medicinal plants in the world which in addition to haring leaves beautiful flowers and decorative application, it also has different applications in pharmaceutical industries cosmetics and hygienic. This plant, in its young leaves has very important alkaloids which called vinblastine and vincristine which has in chemotherapy of different type of cancers (leukemia, breast and lymph nodes) and its roots contain ajmalicine alkaloids that is used in treatment of hypotension. This research was for investigation of the effect of growth regulator and spraying of zinc and magnesium nanoparticles under the conditions of drought stresses on total alkaloids, anthocyanin, total chlorophyll, the weight of wet and dry branches contain alkaloids, and the number of lateral branches periwinkle herb (Catharanthus roseus (L.) G.DON) arranged as a factorial pot experiment based on a completely randomized design which took place in greenhouse condition during years 2020 and 2021 in Tehran, Iran. In the study of the effects of drought stress and spraying of zinc and magnesium nanoparticles on all investigated traits (total alkaloid, anthocyanin, total chlorophyll, fresh and dry weight of alkaloid-containing branches, and the number of lateral branches), there was a statistically significant difference in A level of 1% was observed (P≤0.01). But in the interactions effects of drought stresses and growth regulator showed the highest effect on wet branches contain alkaloids (P≤0.01).