Water shortage is becoming more and more serious in North China，and the influence of urban water crisis is becoming more and more extensive． This paper analyzes the key factor of water shortage in northern cities，and offers the strategies to solve the water shortage problem in North China based on the sustainable use of water resources． The strategy includes rational allocation of local surface water， groundwater，reclaimed water，rainwater，water transfer，and pass-by water resources to improve the urban water supply guarantee rate． A large water network is built to achieve groundwater recharge balance and to ensure the joint dispatch of external water and local water，surface and ground water，conventional and emergency water sources． We select Langfang City as a typical area，a city short of water． We follow the basic principle of water supply-demand balance“water-saving first，water transfer second，water pollution control first，water supply second，environmental protection first，water use second”to balance the supply and demand of water resources by an analysis of“three balances”．Based on the results of water balance analysis in typical areas，the average annual water shortage in Langfang in 2030 will be 0．02 billion m3 ( water consumption will be 1．363 billion m3，water supply will be 1．361 billion m3) ，and the water deficit will be 0．1%． This paper supplied the principle of water allocation and the scheme of green water network interconnection for water-lacking cities in North China．