In order to protect the poor, the Church and secular powers respectively carried out the policies of prohibition and limit on paid mutuum (that is usury) in the first centuries of the Middle AgesFrom Charlemagne on, secular powers began to implement the prohibition of usury upon the laityWith the rising of commercial revolution in the High Middle Ages, commercial and productive mutuum gradually increased on the basis of traditional living mutuumFor the sake of the management of the two different mutuum, the Church made the laws of usury systematization to ban paid mutuum for living, and also regarded commercial and productive mutuum as the exceptions of usury laws, which permitted paid loan or interest legalizationMeanwhile, the revival of the studies of Roman laws let secular powers obtain the conception of protecting creditors rights and the legal knowledge of debts, thus giving rise to the legislation of debt and judicial aid in monarchical laws and common lawsHencethe differential management mode for living, productive and commercial mutuum formed in the high and late Middle Ages in Western Europe, which was helpful for the development of capital market