A single-light source low concentration ozone concentration detector comprises two gas dividers, a zero gas processing device, a gas circuit switching device, a detection cell, a signal amplifier, an AD converter, a flow sensor, a temperature sensor, a pressure sensor, a control processing module, a display device and a gas pump; the detection cell comprises an ultraviolet lamp tube, a lamp chamber, a gas chamber and an ultraviolet light intensity probe, the ultraviolet lamp chamber is provided with a light hole, two end portions of the gas chamber respectively align at and are perpendicular to the light hole and the ultraviolet light intensity probe, the gas chamber is provided with a gas inlet and a gas outlet, the input end of the first gas divider is connected with the gas source, the output end of the first gas divider is respectively connected with the input ends of the zero gas processing device and the second gas divider, and the output end of the zero gas processing device is connected with the input end of the gas circuit switching device; and the output end of the second gas divider is connected with the pressure sensor and the gas circuit switching device, the output end of the gas circuit switching device is connected with the gas inlet of the gas chamber, the input port of the flow sensor is connected with the gas outlet of the gas chamber, and the output port of the flow sensor is connected with the gas pump.