The invention relates to a novel process for realizing the catalytic cracking of heavy oil with large catalyst-oil ratio. By introducing a solid-solid heat exchanger (4) between a regenerator (2) and a riser reactor (3), heat generated by a cooling regenerant is used for heating an agent to be regenerated to return to the regenerator (2), so that the reaction temperature in the regenerator (2) can be maintained under the condition of operation with large catalyst-oil ratio. Therefore, the regenerating process is normally carried out, the regenerating efficiency is ensured, the thermal balance of the entire device is kept, the stable operation with maximum catalyst-oil ratio is realized, the slag doping ratio is enhanced, and the liquid yield of the device is also enhanced, so that the benefit of the device is enhanced.