Abstract: Activated corrosion products (ACPs) in the cooling loops are the dominant radioactive source in water-cooled fusion reactors, and make a great effect on radiation shielding design, personnel protection, and consequences of nuclear accidents. In this paper, a code named CATE (corrosion, activation and transport evaluation) was developed to simulate the production and transport process of ACPs in water-cooled fusion reactors. Based on a two-phase homogeneous model, the concentration balance equations were built, in which the main behaviors of ACPs in the cooling loop were covered, including corrosion, release, dissolution, deposition, activation, decay and purification. For solving the concentration balance equations numerically, the classical method of Runge-Kutta was adopted. The cooling loop in the divertor of ITER (International Thermonuclear Experimental Reactor) was simulated to test the CATE code, and the composition and radioactivity of ACPs respectively in the coolant and on the pipe wall were calculated. These results were compared with those from other two codes PACTITER and TRACT, which presented a consistency in quantity and a reasonable variation tendency over time. Therefore, CATE can be used to calculate the source term of ACPs in ITER and CFETR (China Fusion Engineering Test Reactor), as well as the liquid metal cooled reactor after adding the corresponding database in the future.