In this paper

the interaction between the lines on the same tower and the propagation characteristics of lightning traveling waves when they encounter the lines on the same tower are analyzed

and the lightning strike on the positive pole of Fuyan line of Zhangbei Flexible HVDC Transmission Project is simulated. By comparing the simulation with the actual waveform

the characteristics of the positive electrode voltage and current waveform on each side of Fuyan line and Zhongyan line and the characteristics of lightning wave propagation are analyzed.The results showed that when the lightning current hit the Fuyan line

the lightning wave propagates to both sides of the Fuyan line

and induced lightning wave is generated on the Zhongyan line due to electromagnetic coupling

which propagates to both sides of the Fuyan line. Moreover

the travelling waves of different modulus incident on both sides of the line demarcation point will cross refract at the demarcation point

which causes the difference of induced lightning waves in two sides of the Zhongyan line.After that

both the lightning wave and the induced lightning wave are refracted and reflected at the converter station.The combined action of the above factors will cause the disturbance of the line voltage and current in the normal operation on the same tower

and can cause traveling wave protection action.This research have reference significance for the prevention measures when facing lightning strike on DC lines on the same tower and the setting of the relay protection logic of the DC line traveling wave relay protection device.