Pinker′a Loop Theory(1999)proposes that syntactic structure can enter the formation process of compounds, which is exemplified in English and German but the compounds and derivatives are difficult to be made sophisticated change because they are not real words. This paper aims at using the Loop Theory to probe into the origin of monosyllabic Chinese Reaultative Verb Compounds(RVCs), holds that the formation of Chinese RVCs is a morph—syntactic process, and assumes that Chinese RVCs are formed through the interaction of the pattern associator memory and symbol—pro- cessing rules which provide strong evidence for the economy principle of UG and assure that the baby is burdened with one set of rules or principles instead of two or more sets, which is easier for them to acquire their mother tongue.