Hollow core terahertz (THz) fibers have attracted attention due to the low loss and easy modification with functional materials.Liquid water has unique properties in the THz region and has been widely investigated in THz emission,sensing and devices.In this paper,a THz hollow core Bragg fiber (HCBF) with a water defect layer is proposed.The finite element method is used to analyze the temperature characteristic of the water-filled THz fiber.The numerical analysis results show that the peak of the confinement loss can be controlled by adjusting the temperature of the liquid water,and the confinement loss increases with the increasing temperature of the liquid water in the frequency range of 0.34 THz to 0.44 THz.Moreover,the THz fiber has a high core power fraction up to 98.6%.The proposed THz water-filled fiber may have great potential as a sample cell for THz interaction with liquid and THz controllable devices.