Background: The genus Psammogeton Edyew. which belong to the umbelliferae family, is found in central areas of Asia. This genus consists of six species widespread in the sandy dunes of deserts. Among the four species present in Iran, Pssamogeton canescens (DC.) vatke is distributed in regions of Iran central. Objective: The aim of this study is to determine the chemical composition of essential oil of Psammogeton canescens. Methods: The essential oil was extracted by hydrodistillation of dried aerial part of plant and analysed by GC and GC/MS. Results: Thirty constituents representing 99.7% of total oil have been identified. The main constituents of the oil were found to be β-bisabolene (33.35%), Apiole (28.34 %), α-Pinene (11.86%) and Dill apiole (8.17%). Other representative compounds were identified as β-Pinene (2.68%), Myrcene (2.62%) and sylvestrene (2.42%). Conclusion: Amounting to 99.7% of the total oil, the sesquiterpene hydrocarbons and oxygenated sesquiterpene had the highest contribution (78.16%), these fractions dominated by β-bisabolene (33.35%), followed by Apiole (28.34%) and Dill apiole (8.17%). The diterpene was very poor it represented (0.49%), it is found to contain only a few percent of cembrene (0.49).