Sweet basil (Ocimum basilicum L. var. Grand Vert) is an herbaceous plant that uses volatile oil and herbs in the market or as an ornamental plant. The experiment is divided into two parts, the first is the preparation of chitosan Nano-fertilizer as well as (CCS) and chitosan-NPK nano-fertilizer (CCS-NPK)  as well as loaded on chitosan, and the second part is the application of the use of these different nano- fertilizers, which is recommended by NPK to study its effect on the morphological, chemical and oil properties and its chemical composition for sweet basil plants (Ocimum basilicum L. var Grand Vert). after planting it In the seasons 2017/2018 and 2018/2019 In the Experimental Field of a Medicinal and Aromatic Plants, EL- Qanater El-Khaieria Gezeret El-Shaeier, and the Medicinal and Aromatic dept Lab., (HRI), (ARC), Dokki, Giza, and Nanotechnology and Advanced Materials Central Lab., The study was the effect of Nano-fertilization and toxicity on the plant extract in order to ensure the safety of using nanoparticles. The results revealed that application of chitosan alone or as loaded on NPK or as NPs increased growth, yield, oil %, oil yield, the chemical structure of basil plants, and decreased toxicity of human hung cells, where the effective treatments were CS-NPK NF 400:50:300; CS-NPK NF 300:60:400 and Chitosan Nano 250 under the study conditions.