The malfunction of short-circuit protection became increasingly serious in the fully mechanized face casused by large power equipment, more kind of loads and long distance power. According to the field requirements, the electrical characteristics between motor starting and three-phase short-circuit are compared, the phase-sensitive protection circuit combining current signal amplitude with power factor is designed, the protection data is tested and the protection characteristic is analyzed. The phase-sensitive protection circuit has been uesd in KJZ-4000-10（6）/3.3 flameproof and intrinsically safe load control center. The circuit is stable, sensitive and reliable. It has been proved that the short-circuit protection of power in underground is reliably realized.