Multiple-scattering effects sometime bias the ground-based lidar measurements, in particular for density aerosol and cirrus cloud. Both analytical and Montecarlo methods are very useful tools to study this influence. However, for analytical solution, it needs to make some hypotheses and the Montecarlo simulation is only a forward method. In this paper, an itinerative method is introduced based on Montecarlo simulation. Both extinction and backscattering coefficients, obtained by Raman lidar, are corrected for the multiple-scattering influence. For the typical cirrus cloud, the error of the multiple-scattering influence on extinction can be as large as 100%. However, it is negligible of the influence on backscattering coefficient. Therefore, the lidar ratio is also sensitive to the multiple-scattering effect.