Hydraulic turbine runners and blades are the core components of the Hydraulic turbine, but they are prone to cavitation in varying degrees during long-term operation. Laser additive remanufacturing can be used as an effective repair method for such defects due to its high efficiency, low heat input and good bonding performance. In this paper, a three-dimensional finite element model for laser additive remanufacturing of hydraulic turbine blades is developed, and the transient distribution laws of temperature field and stress field in the laser additive remanufacturing area are calculated. The results show that the influence of laser additive remanufacturing process on the instantaneous temperature and stress of hydraulic turbine blades is mainly concentrated near the additive remanufacturing area. The heat affected range of single laser additive remanufacturing is about 10 mm, and the heat affected range of four laser additive remanufacturing increases to 25 mm. The deformation generated in this process is very slight. The maximum deformation generated by the central cross section is 0.15 mm when the four-channel laser additive remanufacturing is completed, which has little effect on the overall turbine blade.