The invention discloses an uninterruptible power supply circuit, which comprises a bidirectional selection switch, a first-class bidirectional converter, a second-class bidirectional converter, an energy storage device and a filtering device, wherein the bidirectional selection switch is alternatively connected with an alternating-current power supply and the energy storage device; the first-class bidirectional converter is arranged between the bidirectional selection switch and the filtering device; the second-class bidirectional converter is arranged between the filtering device and a load; and both the first-class bidirectional converter and the second-class bidirectional converter have rectifying or inverting functions. Due to the adoption of the bidirectional converters and the bidirectional selection switch, alternating-current mains supply, the energy storage device and a charger needed by the energy storage device can share the bidirectional converters. Compared with the conventional uninterruptible power supply circuit, the uninterruptible power supply circuit disclosed by the invention has the advantage that an additional charger or a high-power inverter is not needed, so that the circuit structure of the uninterruptible power supply circuit is simplified.