The invention discloses a control method and a control circuit of a switching circuit and the switching circuit. The switching circuit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube and an inductor. The first switch tube and the second switch tube are connected in series. The first switch tube is connected to an input end. The third switch tube and the fourth switch tube are connected in series. The third switch tube is connected to an output end. The fourth switch tube is connected to the ground. When the switch circuit works in the BUCK-BOOST mode, the first switch tube and the fourth switch tube are switched on at the beginning of a switching period. Meanwhile, the second switch tube and the third switch tube are switched off. When the inductance current is larger than a first threshold value, the first switch tube and the third switch tube are switched on and the second switch tube and the fourth switch tube are switched off. After afirst period of time, the second switch tube and the third switch tube are switched on and the first switch tube and the fourth switch tube are switched off. When a clock signal is changed from invalid to valid or a second period of time has passed, the switching period is ended. Meanwhile, the next switching period is started. The magnitude of the ripple wave of the inductance current is adjustedby adjusting the first period of time, so that the efficiency of a switching power supply is optimized.