CaCu3Ti4O12(CCTO) thin films were fabricated on ITO-covered MgO(100) substrates.The rectification characteristics were observed in the CCTO capacitance structure with Pt top electrodes at temperatures ranging from 150K to 330K, which are attributed to the formation of a Schottky junction between n-type semiconducting CCTO and Pt due to the difference of their work functions.At low forward-bias voltage, the current-voltage characteristics of the Schottky junction follow J＝JsD exp(pV/koT).A strong decrease in ideality factor with the increasing temperature is obtained by linear fitting at the low bias voltage.