With requirement of household heat metering, variable-flow heating network is future trend, but it's difficult to heating according to users' demand because of hydraulic disorder, which is caused mainly by individual user's regulation. Self-operated pressure difference control valve (SPDCV) is widely used in heating system to solve this problem. This paper concentrates on effect of users' flow reduction on other non-regulated users' flow with constant pressure difference of heating network (CPDHN) and constant pressure difference of the end user (CPDE), and change of pressure diagram. Equal pressure drop of parallel user based on Kirchhoff's voltage law is used to theoretical model, and influencing law of users' regulation is obtained. The results are as follow: (1) user's pressure drop is larger than design pressure drop with CPDHN, and is less than design pressure drop with CPDE when any user's flow is reduced; (2) the front non-regulated. users' flow is increased little, and the middle ones take second place, and the back non-regulated users' flow is increased greatly when any user's flow is reduced with CPDHN; (3) the front non-regulated users' flow is reduced greatly, and the middle ones take second place, and the back non-regulated users' flow keep constant when any user's flow is reduced with CPDE. The conclusion can be got that CPDHN is better than CPDE with any user's flow reduction.