A thermocouple fixing device and a temperature measuring apparatus including a fixing joint, a sealing sleeve, a clamping piece and a locking nut sequentially sleeved outside the outer cover of the thermocouple is disclosed. The inside end of the fixing joint is fixed on the side wall of the vacuum generation chamber, the outside end of the fixing joint abuts on one end of the sealing sleeve; the two sides of the clamping piece abut on the other end of the sealing sleeve and the inside end of the locking nut, respectively; the internal threads of the locking nut are meshed with the external threads of the fixing joint; the clamping piece has a clamping element and a through hole for clamping the outer over of the thermocouple.