Abstract: A design method of high power rotary-field phase-shifter is introduced. By considering the ferrite material,structure and microwave performances, an X-band phase-shifter having high phase-shift accuracy, low insertion loss modulation and high power capability is developed. Its peak power is larger than 1700 W,average power is larger than 200 W,phase shift accuracy is better than 2°,and transition time is less than 300 ms . This is a novel method in structure designing and power considering which can provide new ideas for designing similar products.