An experimental layout was carried out at El-Maghara Experimental Research Station (North Sinai), Desert Research Center, Egypt, during the two successive seasons of 2012 and 2013, to study the effect of the interaction between foliar spraying with silicon at 0, 5 and 10 g/L and different rates of magnetite application (0, 200 and 300 kg/fed) on growth, yield, oil production and chemical constituents of Majorana hortensis L.plant. The best results from all the tested parameters, plant height, fresh and dry weights (g/plant), volatile oil percentage and oil yield/fed were significantly increased with using the second level of magnetite application (200 kg/fed(. Also using silicon as foliar application at 5 g/L led to the best results of the same parameters. In addition, the vegetative growth, oil production as well as chemical constituents (Si, Fe, Ca, N and total carbohydrates content) were improved by the interaction between silicon and magnetite application, and the highest significant increase in all parameters were recorded with using the second level of magnetite (200 kg/fed) and spraying with silicon at 5 g/L, the main component of the volatile oil resulted from this treatment was 1-4-terpineol (29.75%), followed by trans-sabinene hydrate (21.28%), α–terpinene (16.45%), α–terpineol (8.45%), sabinene (6.99 %), P-cymene  (3.29%), linalyl acetate (2.97%), trans-carophyllene (2.93%), α–terpinolene (1.93%),  L-linalool (1.59%), α–pinene (1.3%) and D-limonene (1.01%). While, using silicon and magnetite caused decease in Na, Cl and proline contents in marjoram plant.