Abstract: The liquid molten salt reactor uses liquid molten salt as fuel, and the fuel flows in the primary loop driven by a main pump, resulting in reactivity loss in the process of flow. Considering the effect of fuel flow on core power control, a nonlinear model is established and linearized. Based on the core linearization model, the LQG/LTR technology is used to design the core power control system. Taking the molten salt experimental reactor as an example, the core reactivity disturbance control is studied. The results show that the LQG/LTR technology can be used to control the core power of liquid molten salt reactor.