A battery cover assembly for a portable electronic device, the battery cover assembly includes a housing, a removable battery cover and a locking mechanism. The housing defines an opening and a receiving hole communicating each other. The removable battery cover includes a protrusion. The locking mechanism includes a latching member and an operating member. The latching member engages in the opening of the housing, the latching member forming a post engaging with the protrusion of the cover. The operating member engages in the receiving hole of the housing, and the operating member rotatably brings the latching member to releasably lock the post with the protrusion of the cover.