The invention discloses a true triaxial test device capable of testing rock heat conductivity coefficients. The device comprises a sigma1-direction loading system, a sigma2-direction loading system and a sigma3-direction loading system. The sigma1-direction loading system comprises a vertical loading piston and an upper pressure head; the sigma2-direction loading system comprises a pumping loading portion and a manual loading portion; the sigma3-direction loading system comprises an oil delivery pipeline. The vertical loading piston is arranged above the upper pressure head which is arranged at the upper end of a rock sample, a base is arranged at the lower end of the rock sample, horizontal pressure heads are arranged at left and right ends of the rock sample respectively, and the oil delivery pipeline is connected with a hydraulic servo pump. By the true triaxial test device, defects that existing rock mechanical tests and heat conductivity coefficient tests are conducted separately and conventional triaxial test device for the rock heat conductivity coefficients fail to accurately reflect heat conductivity coefficients of rock under a real load bearing state are overcome. The true triaxial test device has advantages of reasonable structure, easiness in operation and high accuracy.