Simple p_n diodes have been fabricated by direct growth of La0.9Sr0.1MnO3 thin films on n_type silicon substrates.These junctio ns exhibit good rectifying characteristic in a wide temperature range from 50 to 280K.Large magnetoresistance up to 70% was observed in a low field of 3×10-2T in th ese junctions.The junction magnetoresistance depends on bias and temperature.