This study was carried out at green house on National Research Centre during two successive seasons of 2020-2021 in Giza governate. The aim objective of this work was to investigate the effect of spraying different levels of algae (0, 10 and 15%) on vegetative growth and chemical constituents of Jatropha curcas L. seedlings grown under various salinity concentrations (0, 2000, 4000 and 6000 ppm). Our results showed that, spraying algae at 15% increased both of (plant height, leaves number/plant, stem diameter, root length, branches number/plant, main flowers number/plant, sub-main flowers number/plant, fresh and dry weight of stem, leaves and roots, chlorophyll a, b, a+b and carotenoids, protein contents and total carbohydrates percentage), while a significant reduction in all the same parameters, were occurred by using high salinity level (6000 ppm). The combined proline and phenols contents decreased by using 10 or 15% algae, compares of treated as the control. The results suggested that Jatropha curcas L. seedlings benefited the application of algae especially under salinity concentrations grown in sandy soil.