Nano Fe₃O₄ was prepared by chemical co-precipitation and characterized by XRD. Different smoke compositions were made using micron Fe₃O₄,micron TiO₂,nano TiO₂/Fe₃O₄ and nano Fe₃O₄ as oxidizer and their burning property and infrared extinction capability were studied by DTA and infrared transmission percentage test. The results show that the exothermic peak of the smoke composition with nano Fe₃O₄ accelerate 28 ℃ compared to that of smoke composition with micro TiO₂,whereas its burning rate and infrared extinction capability are improved. The results indicate that the smaller particle size of oxidizer as well as the faster burning rate of smoke composition is,and the infrared extinction capability decrease with the increase of oxygen content in oxidizer.