An electrical connector and a method for mating and unmating the same. The electrical connector comprises a housing, a locking arm, a biasing member, and a sliding member. The locking arm comprises a first end, a second end, and an intermediate portion between the first end and the second end. The first end comprises a locking portion. The intermediate portion is pivotably mounted to the housing about a pivot. The biasing member is engaged with the locking arm to drive the first end in a first direction. The sliding member is slidably connected to the housing and configured to slide in a second direction perpendicular to the first direction. The electrical connector may be securely locked to a mating electrical connector and has a compact structure, allowing the mating electrical connector to be mounted on a circuit board that has a compact structure.