Parallel—outermost strategy is widely used in reduction systems．Parallel—outermost pattern matching studies the pattern matching method adapted to the strate-gy．By preproeessing the patterns into an adaptive pattern matching automaton APMA，this paper takes advantages of local matching information of unsuccessful matching states to build parallel—outermost pattern matching automaton POPMA．By use of POPMA，all of parallel—outermost pattern matching subterms can be gotten through a single scan．The method limits the size of the automaton，avoids the overheads in the naive algorithm and makes the good relation between the pattern matching and the reduction strategy．POPMA also can be used to improve parallel—outermost strategy．