Abstract: In order to measure the wet steam parameters with laser scattering method, monitor the steam humidity at the final stage and guide the safe operation of turbine, the multi-population genetic algorithm was adopted, cubic spline interpolation was used in stead of scattering theory, the least squares of theoretical value and measured value were adopted as the objective functions and the appropriate control parameters were set up for searching the optimization among the simulation data added Gaussian white noise and the experimental data of analog cylinder. The experimental results show that multi-population genetic algorithm can effectively restraint premature convergence, locate the global optimal solution accurately and inverse every parameter of wet steam prominently among some hereditary algebras. The study is helpful for the measurement of wet steam parameters with laser scattering method and the inversion of particle size distribution.