The invention provides a control circuit and method based on a dual-tube buck-boost converter. The circuit comprises a sampling module, a comparison control module and a drive module. The comparison control module comprises a mode adjusting judging unit, a voltage difference matching unit and a self-adaptation control unit. The circuit has the advantages that the working state of the dual-tube buck-boost converter can be automatically judged so as to control the dual-tube buck-boost converter to work in the boosting mode or the bucking mode or the passing mode, the circuit can be effectively subjected to smooth conversion between the boosting mode and the bucking mode through transition in the passing mode, and therefore the system stability is ensured.