Magnetic and transport properties for the series of (La 0.67 Ba 0.33 MnO 3 )/(Bi 2 O 3 ) x/2 and (La 0.67 Ba 0.33 MnO 3 )/(TiO 2 ) x have been studied. The doping Bi almost has no influence on the magnetization M and Curie temperature T c , but remarkably improves the low-field magnetoresistance at low temperature. On the contrary, doping Ti depresses (M) and lowers T c and peak resistivity temperature T p , accompanying the rapid increase in the resistivity, and increases the high-field magnetoresistance at low temperature obviously. Different physical mechanisms are discussed for these different behaviors. The surface state of the particles is a key factor influencing on the magnetoresistance effects. Small amount addition of Bi or Ti can improve the room temperature magnetoresistance obviously. These results are favorable for the application studies.