It was found that in the half-wavelength line, the terminal voltage of the fault phase was low under external fault. While the middle section of the line failed, the terminal voltage of the fault phase was close to the rated value. Based on this feature, a comprehensive protection scheme was proposed, which combined the characteristics of the terminal voltage with Bergeron current differential protection. The terminal voltage auxiliary criterion and the Bergeron differential current criterion with different high and low sensitivity were combined to protect the full length of the line so as to realize the fault phase selection. Then a half-wavelength transmission line model was established based on MATLAB/Simulink platform to carry out simulation verification. The simulation results show that the protection scheme can reliably protect the full length of half-wavelength lines and accurately identify fault phases.