The particle size of gas phase oxided titanium dioxide that manufactured in a China′s company was measured with a Malvern laser particle size analyzer.The effects of refractive rate,absorption rate and shading degree on the particle size of titaniumdioxide were studied.Results showed that the refractive rate was related to the crystal structure of the material.As the absorption rate increased,the residual value decreased first and then increased.When the shading degree was more than 20%,the average particle size decreased obviously and the residual value increased.The optimum parameters of the gas phase oxided titanium dioxide measured by the laser particle size analyzer were determined as follows: the refractive rate was 2.71,the absorption rate was 0.1 and the shading degree was 10%.Under the optimum conditions,the average particle size of the sample was 0.329 μm,and the particle size was normally distributed which was consistent with the results of SEM.