The present investigation was carried out to investigate effects of TiO₂ nanoparticles on growth and chemical composition of fennel plants . Previous work showed that TiO₂ nanoparticles could significantly raise photosynthesis and greatly improve growth of fennel (Feoniculum vulgare Mill) plants . The plants were sprayed with different concentrations of TiO₂ nanoparticles 2, 4 and 6 ppm . The results showed that, TiO₂ nanoparticles at treatment 6 ppm could obviously get  the highest number of branches , the tallest plants , the highest fruit yield per plant and the highest values of Pigments,Carbohydrates, phosphorus ,Sugars nitrogen , potassium . sprayed fennel plant with concentrations of TiO₂ nanoparticles 0, 2, 4 and 6 ppm is safe for human .