An optical fiber connector includes an outer sleeve and a main casing body. The outer sleeve includes a surrounding wall and a key portion extending forwardly from the surrounding wall. The main casing body includes a wall portion defining a mounting space for receiving a portion of a mechanical transfer (MT) ferrule mounted with a plurality of optical fibers therein. The outer sleeve is detachably sleeved on the wall portion. The wall portion has two opposite outer connecting surfaces formed respectively with two keyways. The key portion engage one of the keyways. The outer sleeve is detachable from the main casing body so as to allow the key portion to engage the other one of the keyways.