The　paper　reports　the　formation　and　crystal　structure　of　dihydronitidine,　expounds　the　reasons　and　conditions　of　easily　formed　oxynitidine,　and　discusses　anticancer　mechanism　of　nitidine　(cation).　The　crystallographic　parameters　of　dihydronitidine　are:　space　group　P2(1)/n,　a　=　12.54(1),　b　=　9.148(5),　e　=　14.748(8)　angstrom,　beta　=　92.12(6)-degrees,　Z　=　4.　4108　independent　reflections　were　collected　within　the　range　of　3-degrees　less-than-or-equal-to　2theta　less-than-or-equal-to　54-degrees,　of　which　2137　intensity　data　with　1　greater-than-or-equal-to　3sigma(1)　were　used　in　the　structural　determination.　The　crystal　structure　has　been　refined　by　full　matrix　least-square　method　to　a　final　R　of　0.050.