The　Direct　path　and　multipath　interference　(DPI　and　MPI)　Cancellation　is　a　crucial　issue　in　the　passive　radar.　In　this　paper,　two　improvements　have　been　done　in　NLMS　algorithm.　One　is　to　estimate　the　values　and　distribution　of　DPI　and　MPI　roughly,　and　then　remove　them　from　the　echo　signal　before　filtering.　The　other　one　is　to　vary　the　step　size　of　NLMS　according　to　the　cross　correlation　function　of　the　reference　signal　and　the　output　signal　of　the　adaptive　filter.　The　performance　of　the　improved　algorithm　in　passive　radar　DPI　and　MPI　Cancellation　is　reported.　The　computer　simulation　results　show　that　the　algorithm　has　a　faster　convergence　rate　and　a　smaller　steady　state　error.　©　2012　IEEE.