In the present paper, the empirical LAI dynamic model was constructed using the MOD15A2 data set, and the canopy radiative transfer model MCRM2 was coupled with the LAI dynamic model through LAI. The scheme was proposed to retrieve LAI by assimilating MOD09A1 data set into the coupled model. The ensemble Kalman smoother (EnKS) method was first introduced. In order to preferably assess the feasibility of EnKS, the LAI retrieval results of EnKS were compared with the ensemble Kalman filter (EnKF) solutions and MODIS LAI product. The results indicated that the EnKS method achieved ideal results. The retrieved LAI temporal profiles by the EnKS method were smoother and more continuous than the EnKF solutions and the MODIS LAI product, which were in good agreement with the realistic LAI climatology. The developed inversion method in this paper can be applied to retrieve LAI time-continuous profiles effectively.