This paper mainly discusses the interest allotment of enterprise alli ance.Directed to the uncertainty and the inequality that results from imperfect information of market.Two new concepts are put introduced:reliance degree and di scount factor.An interest allotment model of unequal alliance under uncertain en vironment is built theoretically.This model completely analyses the first-mover advantage and last-mover advantage and the situation under which enterprise al liance can not be formed.