An expansible anchor assembly includes an expansion sleeve and an anchor bolt plugging and expanding the expansion sleeve. The expansion sleeve includes a first end, a second end, an expansible member adjacent to the second end that is divided into expansible segments by slits, and a bore defined in the expansion sleeve for communicating the first end with the second end. A groove is annularly formed on the expansion sleeve, and a distance from the groove to the second end equals to ¼˜⅖ times a length of the expansion sleeve for preventing an over length of the slits, which is beneficial to the manufacture. During expansion, the expansible segments are completely expanded when the expansible member is subjected to a thrust from the anchor bolt to promote the anchoring force and avoid damaging a working wall.