By way of doping excessive Ag~(1 ) ion in LaMnO_3,it is found that on the sample's magnetoresistance curve two peaks appear when socalled x=0.3 and x=0.65 at room temperature.At H=1.8 T the sample's MR achieve-23.0% and22.7% respectively.However,it must be pointed out that the true Ag contents are usually less than the calculated contents,because Ag will separate out from samples.The huge magnetoresistance effect in the sample of x=0.3 seems to be independent of Agrich phase,while the huge magnetoresistance effect in the sample of x=0.65 has close correlation with Agrich phase.In the tested sample,Ag,perovskite and hole reach the optimum ratio,and so,lead to a strong fieldinduced enhancement in percolation.