Abstract: Tin dioxide (SnO↓2)powder was synthesized by microwave heating method with tin chloride dihydrate as main raw material.The prepared powder has been characterized by particle analyzer，specific surface area analyzer，SEM and XRD etc..The results showed SnO↓2 particles were the resultants of the reaction through microwave heating process.The concentration of the reactant，pH，microwave heating power and reaction time all had effect on the particle size.The SnO↓2 powder could be prepared under the following conditions：amount of tin chloride dihydrate 0.84 g；power 400 W；solution pH 1.9~3.0；reaction time 20 min；and concentration of the reactant 3.5 mol/L.It could be seen from SEM photographs that part of the SnO↓2 particles synthesized by microwave heating method were nano-sized particles.