The invention relates to the technical field of charging and discharging technologies, and discloses a charging and discharging circuit and a multi-port input and output system. The circuit comprisesa switching tube Q1, a switching tube Q2, a switching tube Q3, a switching tube Q4, a switching tube Q4, a switching tube Q5, an inductor L1, an inductor L2, a capacitor C1 and a capacitor C2, whereinone end of the switching tube Q1 is connected with one end of the switching tube Q2 and one end of the inductor L1, the other end of the inductor L1 is connected with one end of the switching tube Q5and one end of the inductor L2, the other end of the inductor L2 is connected with one end of the switching tube Q3 and one end of the switching tube Q4, the other end of the switching tube Q4 is connected with one end of the capacitor C1, the other end of the switching tube Q5 is connected with one end of the capacitor C2, the other end of the switching tube Q2 is connected with the other end ofthe capacitor C2, the other end of the capacitor C1 is connected with the other end of the switching tube Q3. Through improvement on the BUCK-BOOST circuit, the synchronous output of the different voltages is achieved, and the circuit is simple in structure, convenient to expand, and can be discharged while being charged.