This study investigates i) the determination of iron oxide nanoparticles (Fe3O4 NPs) from the phloem-sap of pumpkin plants by using transmission electron microscopy (TEM), and ii) impact of Fe3O4 NPs on the metabolite composition of the phloem sap. For these purposes, pumpkin seedlings were treated by 100 mg/L of Fe3O4 NPs (with a nominal size of 10 and 40 nm) for one week. The phloem sap of the plants (NPs-treated and un-treated (control)) were extracted and analyzed by TEM. Metabolite changes of the phloem sap were determined through gas chromatography-mass spectrometry (GC-MS). The results showed that Fe3O4 NPs (both 10 and 40 nm) exist in the phloem sap of pumpkin, revealing its translocation to the aerial parts of the plant. Compared to nontreated control, NPs-treatment significantly increased the abundance of phloem sap-metabolites, which are related to oil metabolic pathway, such as methoxyacetic acid 4-tetradecyl ester (19.7 %), eicosane (5.46 %), and heneicosane (7 %). In opposite, the content of some oil compounds was found to be decreased, such as decosane (24.2 %), hexadecane (6.78 %), and 4-hydroxy-4-methyl-2-Pentanone (7.08 %). These results revealed that Fe(3)O(4)NPs translocated to the aerial parts and can alter the abundance of oil-related metabolites, which may affect oil composition of the plant.