The embodiment of the invention provides an organic carbon analyzing device. The device comprises a distributor, a delay coil, a quartz glass tube, a first electrical conductivity sensor, a second electrical conductivity sensor and a signal amplifying module; a water sample is divided into two equal parts through the distributor, one part of water sample enters the first electrical conductivity sensor, the first electrical conductivity sensor obtains the total inorganic carbon concentration signal of the water sample, and when the other part of water sample passes through the helical quartz glass tube coated with titanium dioxide, organic matter in the water sample is irradiated by an ultraviolet lamp and catalytically decomposed into carbon dioxide. The total carbon concentration signal of the water sample is obtained through the second electrical conductivity sensor, and the total carbon concentration is the difference between the total carbon concentration and the total inorganic carbon concentration. By means of the embodiment, the defect that a traditional total organic carbon analyzer detects organic carbon in purified water by using an electrical conductivity method, the signal of an electrical conductivity sensor is very weak, so that the measurement precision is poor is overcome, and the measurement precision of the total organic carbon in the purified water is improved.