Abstract: In order to study the characteristics of the wet steam in steam turbine unit, the new measurement method based on laser backscattering method was proposed to get the data of scattering light intensity of the wet steam at different angles and at different locations. And then, the parameters of the wet steam were gotten and the middle radius of the wet steam droplets quality was about 1μm. The results show that the blank data of none wet steam also has the impact on the wet steam method, so the formula should be corrected. And no matter there is the wet steam or not, the scattered light intensity at 30° is about 1.5 times of the scattering light intensity at 60°, so the scattered light at 30° is more suitable for measurement. The results show that the backscattering theory is feasible for wet steam measurement.