An electrical connector assembly includes a first connector and a second connector inserted to a front of the first connector. The second connector has a casing. A latch portion is protrudingly provided above the casing. The first connector includes a shell. A locking arm is pivoted to the shell by a pivoting portion, and is provided with a buckling portion for buckling the latch portion. The locking arm includes at least one first position limiting portion and a second position limiting portion in front of the buckling portion. In a separation process of the first and second connectors, the locking arm is actuated, the buckling portion is detached from the latch portion and moves backward, and the latch portion firstly stops the first position limiting portion. After the latch portion is detached from the first position limiting portion, the latch portion stops the second position limiting portion from moving backward.