Improvements made to the cloud removal method for landsat MSS images proposed by O.R.Mitchell are presented.A more reasonable mathematical model for the cloud effect has been derived,and a two-stage filtering scheme based on this new model has been proposed.A filtering and a 3-Dprocessing method for landsat MSS image noise cleaning has been developed to implement the scheme.A preliminary experiment shows promising results. Improvements made to the cloud removal method for landsat MSS images proposed by OR Mitchell are presented. A more reasonable mathematical model for the cloud effect has been derived, and a two-stage filtering scheme based on this new model has been proposed. A filtering and a 3-Dprocessing method for landsat MSS image noise cleaning has been implemented to implement the scheme. A preliminary experiment shows promising results.