Circular electron-positron collider (CEPC) is a double ring collider with a circumference of 100 km and a maximum energy of 120 GeV. To meet the needs of different energy particles injected from the booster to the collision ring, an off-axis injection system of the collision ring is designed for the W and Z energy modes to realize the accumulation of beam. To improve the injection efficiency, also be compatible with different injection energy, and different beam filling modes, and at the same time reduce the disturbance of other bucket by the kicker magnet during the injection process as much as possible, the off-axis injection kicker magnet system of the collision ring is required to be a trapezoidal wave pulse discharge system with a rise time and falling time of less than 200 ns and a pulse bottom width adjustment range of 440-2420 ns. Compared with the common lumped-inductance kicker magnet, the delay-line kicker magnet has better dynamic response characteristics and is suitable for producing a trapezoidal pulse with steeper front and more ideal waveform. In this paper, according to the physical requirements of beam injection of CEPC, the physical design and structure design of a delay-line kicker magnet are completed, and the PSpice and Opera programs are used for simulation. The design results show that the delay-line kicker magnet is composed of 26 LC units superimposed. The total length of the kicker magnet is 1018 mm, and the magnetic effective length is 942 mm. In [-20, 20] mm magnet aperture, the magnetic field strength is 0.042 1 T, the magnetic field uniformity is better than ±0.2%; the total rise time (10%-90%) of the kicker magnet system is 193 ns, and the fall time (90%-10%) is 191 ns. Theoretical analysis, PSpice program and Opera program simulation all verify the feasibility of the magnet design scheme.