Abstract: CaOloaded solid base used in transesterification of rape oil was prepared by loading CaO on MgO. The base strength and content of the solid base at different preparation conditions were analyzed. The solid base belonged to superbase with the base strength of 27.0 < H- < 37.0. After dipped in 22.4% Ca(AC)2 for 1h and calcined at 700℃ for 24h, highest basic content of the solid base were achieved (H- >9.3, 25.68 mmol/g). The solid base exhibited high catalytic activity in transesterification of rape oil into biodiesel, and the rape oil conversion reached 97.95%.