Abstract: There are many reasons for China’s defeat in the Sino一Japanese War including both lack of technological preparation and mistakes in military strategy.But according to these historical studies,the defeat of the Qing army had even more complex social causes like the corruption of the feudal system and those in control of the army and government, outmoded thinking,and the weakening of military morale and popular resolve.In addition,the Qing government miscalculated the extent of Japanese ambition and actually strength and adopted mistaken military strategies.blindly begging the big powers for support and thus tragically losing the war.The loss of this war greatly aroused every level of Chinese society,giving rise to modern thinking and the movement of political reform.