The invention provides a temperature control device of a splicing objective lens and a temperature control method of the splicing objective lens. The splicing objective lens comprises at least one group of objective lenses, wherein the group of objective lenses comprise an upper objective lens and a lower objective lens which are in light path connection. The temperature control device of the splicing objective lens comprises a water sleeve, an upper water inlet pipe, a lower water inlet pipe, an upper water outlet pipe, a lower water outlet pipe, a water circulation water control unit, an upper temperature sensor, a lower temperature sensor and at least one lower heater, wherein the upper objective lens and the lower objective lens are arranged in the water sleeve, the upper water inlet pipe and the upper water outlet pipe are arranged at the upper objective lens, the lower water inlet pipe and the lower water outlet pipe are arranged at the lower objective lens, the circulation water control unit communicates the upper water inlet pipe, the lower water inlet pipe, the upper water outlet pipe and the lower water outlet pipe, the upper temperature sensor and the lower temperature sensor are respectively near to the upper objective lens and the lower objective lens, at least one lower heater is arranged on the lower water inlet pipe so as to heat circulation cooling water in the lower water inlet pipe by the heater, the temperatures of the upper objective lens and the lower objective lens are balanced and the integral temperature control uniformity is ensured.