La1-x　Sr-x　MnO3(LSMO)/TiO2　pn　heterojunctions　have　been　successfully　synthesized　by　RF　magnetron　sputtering　and　they　exhibit　good　rectifying　properties.　The　diffusion　potentials　increase　with　increasing　Sr　concentration,　which　may　be　attributed　to　the　increased　carrier　concentration.　And　the　diffusion　potential　increases　with　decreasing　measurement　temperature,　which　may　have　resulted　from.　modification　of　the　interface　electronic　structure　of　La1-x　Sr-x　MnO3/TiO2　pn　heterojunction　with　changing　temperatures.　It　is　worth　noting　that　the　metal-insulator　(M-I)　transition　of　LSMO　can　also　be　observed　in　pn　heterojunctions　and　the　increased　sheet-resistance　of　pn　heterojunctions　at　low　temperature　is　related　to　the　introduction　of　TiO2.