A burn-in socket includes an insulative seat with a plurality of terminal-retained passageways, a sliding member defining a plurality of terminal-receiving passageways, a driven frame and a plurality of terminal retained in terminal-retained passageways of the seat and received in the terminal-receiving passageways of the sliding member. Each of the terminal-receiving passageways defines two opposite inner sides. Each terminal includes a base portion, a board-connecting portion and a pair of clamping arm consisting of a movable arm and a static arm, the pair of clamping arms defining clamping end at tips thereof. The pair of clamping arms are located elastically against corresponding inner sides, the static arm defines a lower curved portion with a projecting end and an upper linear portion, the projecting end of the lower curved portion of the static arm elastically presses against the movable arm permanently.