In recent years, it has been shown that the use of chemical fertilizers negatively affects the environment and public health. Nano fertilizer have been discovered and used, and one of their many advantages is the speed and ease of obtaining them from various plant sources, which are cheap and currently available it's friendly for environment. The field experiment was carried out in the spring season of 2021 in a mixture of salty clay (cohesive soil) for the purpose of studying the effect of spraying synthetic nanoparticles used from iron oxide particles with onion plant extract at concentrations of 100, 200 and 300 parts per million on the growth and yield of cucumber (Cucumis melo var. flexuosus). The prepared nanoparticles were identified by the following assays: UV-visible spectrophotometry, XRD, FTIR, TEM, SEM and AFM. The results showed a significant effect of using Nano pesticides, especially with high concentration, in increasing average plant height, plant dry weight, leaf area and total plant yield. It was concluded from this study that the positive effect of Nano-fertilizer prepared with onion extract on plant growth, which led to an increase in cucumber productivity and the quality of its fruits, from that there is the possibility of using it as an alternative to conditional mineral fertilizers, after conducting several studies on the safety of using these plants treated with Nano-fertilizers for humans.