Permanent　magnet　materials　based　on　the　MM2Fe14B　(MM　=　Misch-metal)　are　widely　noted.　However,　as　a　room　temperature　paramagnetic　phase,　the　existence　of　CeFe2　phase　in　MM2Fe14B　alloy　is　unavoidable.　In　order　to　eliminate　the　CeFe2　phase,　the　La　substitution　on　MM　in　MM2Fe14B　alloys　was　described.　Alloys　with　nominal　composition　of　(LaxMM1-x)(33)Fe66B　(x　=　0,　0.025,　0.05,　0.075,　0.1,　0.15)　were　prepared,　and　the　crystal　structure　and　magnetization　of　the　(LaxMM(1-x))(33)Fe66B　alloys　were　investigated.　XRD　results　reveal　that　the　lattice　parameter　a,　c,　unit-cell　volume　V,　and　c/a　ratio　of　(LaxMM1-x)(33)Fe66B　alloys　increase　linearly　with　the　La　increase,　indicating　that　La　atoms　enter　into　the　main　phase.　Key　to　this　study　is　the　finding　that　CeFe2　phase　disappears　with　the　La　content　above　0.075.　It　is　therefore　concluded　that　La　substitution　could　inhibit　formation　of　CeFe2　phase.　This　is　consistent　with　the　observation　from　SEM-EDS.　Another　interesting　finding　is　that　La　substitution　would　cause　the　change　of　Nd,　Pr,　La　and　Ce　ratio　in　main　phase,　which　means　the　ratios　of　four　rare　earth　elements　change　with　the　La　substitution.　With　the　increase　of　x,　the　(Pr　+　Nd)/(La　+　Ce)　ratio　in　main　phase　of　(LaxMM1-x)(33)Fe66B　alloys　decreases　first,　showing　the　lowest　point　at　x　=　0.075,　and　then　increases.　As　a　result,　the　saturation　magnetization　(M-s)　of　(LaxMM1-x)(33)Fe66B　alloys　has　the　same　tendency,　which　decreases　from　11.78　kG　(x　=　0)　to　11.35　kG　(x　=　0.075)　first,　and　then　increases　to　11.96　kG　(x　=　0.15).　And　the　Curie　temperature　(T-c)　displays　the　same　trend　compared　to　the　Ms.　These　facts　show　that　the　MM　has　a　great　potential　to　prepare　the　low　cost　sintered　permanent　magnets.