Abstract: This study was carried out to study the inhibition effect of Fe on tobacco mosaic virus(TMV) infection,and regulation factor on the four composes of calcium signaling system in tobacco leaves.The Ca2+ and CaM content was measured by atomic absorption spectrophotometry and ELISA method,respectively.The activities of Ca2+-ATPase and NADKase in tobacco leaves were evaluated under different iron levels with liquid culture method.The results showed that the resistant ability was strengthened,and the symptom was alleviated when treated with Fe 1.68 mg/L in comparison with those of no Fe treatment.Moreover,the Ca2+ content was decreased and the CaM content and the activities of Ca2+-ATPase,NADKase in tobacco leaves treated with Fe 1.68 mg/L were increased,compared with those of no Fe treatment.These results indicated that iron nutrient could take part in the regulation of the calcium signaling system,and reduce pathogenic reaction of virus infection.The calcium-calmodulin messenger system between tobacco and TMV could play a role in the intercellular signal transduction and affect the physiological reaction for plant disease resistance.