A UPS control circuit and a UPS is provided. The UPS includes a rechargeable battery and a UPS control circuit connected with the rechargeable battery. The UPS control circuit includes an input filtering circuit, a rectification circuit, an inversion circuit, a static transfer switch, an output filtering circuit, a control circuit, and a multipurpose DC/DC circuit connected between the rechargeable battery and an output terminal of the rectification circuit. The multipurpose DC/DC circuit is controlled by the control circuit. In a battery mode, the rechargeable battery supplies an input voltage to the inversion circuit via the multipurpose DC/DC circuit. In a mains power mode, the rechargeable battery is charged by an output voltage of the rectification circuit via the multipurpose DC/DC circuit. Therefore, no independent charging circuit is needed to charge the rechargeable battery, causing a simpler circuit structure and a lower cost, and providing greater value to the customer.