Digital　holography　combines　the　advantages　of　the　optical　holography　and　the　digital　image　processing　as　a　method　for　recording　and　reconstructing　amplitude　and　phase　of　a　wave　field.　Traditional　reconstruction　algorithms　can　only　obtain　image　with　the　fixed　pixel　size.　By　directly　discretizing　the　Reyleigh-Sommerfeld　(RS)　integral　formula,　a　new　reconstruction　algorithm　is　proposed.　Experiment　result　shows　that　the　reconstruction　pixel　size　and　pixel　number　can　be　controlled　with　the　proposed　algorithm.　2009　SPIE.