Abstract: The article introduces a simple method for calculating peak pressure of loop network. The principle of the calculation method using branch network regulator's outlet pressure, which defines peak pressure of loop network, is to determine peak pressure with peak coefficient and rated pressure drop from regulator's outlet at peak coefficient of 1. By this method, operation management unit can define the pressure at regulator's outlet easily according to peak coefficient on the basis of hydraulic calculation result of loop network at rated operation status designed and max. hour flow rate.