The invention belongs to the technical field of isotopic infrared spectrum analysis, and particularly relates to a temperature control device of an isotopic spectrum analysis system. The temperature control device comprises a first sealed heat preservation tank, a second sealed heat preservation tank, a preheating constant-temperature tank and a disturbance device, wherein the first sealed heat preservation tank is located in the second sealed heat preservation tank; the first sealed heat preservation tank and the second sealed heat preservation tank are filled with nitrogen; a sample pool is located in the first sealed heat preservation tank; an air inlet of the sample pool communicates with an air outlet of the disturbance device; and the air inlet of the disturbance device communicates with the air outlet of the preheating constant-temperature tank. The preheating constant-temperature tank is used for preheating to-be-tested gas when the to-be-tested gas enters the sample pool, and the disturbance device can distribute the temperature of the to-be-tested gas evenly, so that the constant-temperature state same as the environment in which the sample pool is located is achieved, temperature fluctuation in the sample pool when the to-be-tested gas is injected into the sample pool at a room temperature is avoided, and the sample pool is kept in an accurate constant-temperature state to improve the measurement accuracy.