Abstract: A novel S-band high-power “hammer-shaped”energy output structure was developed to relax the limitations of large insertion loss and low power capacity of the existing high-power continuous wave injection frequency-locked magnetron.The influence of the new output structure on the insertion loss and magnetron performance was simulated with CST microwave studio.The simulated results show that the new output structure considerably outperforms the old one with an insertion loss lower than-0.002 d B in 2.4~2.5 GHz range, and that its ballradius and ceramic window thickness significantly affect the transmission performance.When integrated with the new output structure, the magnetron starts normally and provides a good output spectrum.In addition, the temperature, thermal deformation and stress profile were simulated.At an input power of 30 k W, the highest temperature rise, the strongest stress and the largest deformation were estimated to be 27℃, 156.759 MPa, and 0.010 mm, respectively.