Root-knot nematodes (Meloidogyne spp.) are one of the most important plant parasitic nematodes in tropical and subtropical regions. In the present study, the effects of various concentrations of Khazra nano iron chelate fertilizer (NICF) containing 9% chelated iron and salicylic acid (SA), the chemical resistance inducer, were studied on M. javanica in cucumber plants. A factorial experiment (SA at the rate of 2 and 4 mM/plant; and iron from the source of NICF, at the rate of 3, 6 and 9 mg/kg soil) was carried out in a completely randomized design with four replications, under controlled greenhouse conditions. For this purpose, the four-leaf seedlings of cucumber, cultivar Super Dominus were treated with different rates of SA and NICF as aerial spray and soil drench, respectively, and sterile distilled water was used as control. Twenty four hours after treatments, seedling were inoculated with 2.5 eggs and second-stage juveniles (J2s) per gram of soil. Eight weeks after nematode inoculation, plant growth indices and nematode reproductive factor were evaluated. To evaluate the time dependent changes in the activity of certain antioxidant enzymes in the leaf tissue of cucumber inoculated with 1000 J2s of M. javanica, treated with 2 mM/plant of SA and 9 mg/kg soil of iron in the form of NICF, an experiment was performed in a completely randomized design with three replicates. Activity of catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) in leaves of cucumber were investigated one day before nematode inoculation (Time 1), simultaneously with nematode inoculation (Time 2), one day (Time 3), two days (Time 4) and three days (Time 5) after nematode inoculation and the enzyme activity were subjected to spectrophotometer, at light absorption of 240, 560, and 470 nm. The results showed that the combination of nine mg/kg soil of NICF and two mM of SA reduced the number of galls, egg masses, eggs and nematode reproductive factor by 60, 39, 40 and 36%, respectively, as compared to control. The highest activity of CAT and GPX enzymes was observed in inoculated plants treated by NICF+SA at time points of 2 and 5 and maximum activity of SOD was observed in inoculated plants treated by SA at time point of 3. Based on the results, treatment of infected cucumber plants to M. javanica with SA and NICF significantly increases the plant antioxidants and reduces the nematode damage.