As the provincial capital of Heilongjiang Province, Harbin is the center city in the north of northeast China and the important manufacturing industrial base. However, because of the geography position and hydrological situations, water using security often occurs, which threatens people's survival and development. In order to ensure the water using security in emergency, this paper analyses some influencing factors of city's emergency water supply from geology, water quality and water pipes. Defining 2005 as the current year, this paper draws a clear prediction of urban water demand of Harbin which arrives a conclusion that in 2020 Harbin will suffer from severe water deficiency. Also, based on analyzing the existing problems on water supply system as well as using relevant domestic researches for references, the influencing factors of Harbin urban water supply risks are summarized which include risk of water supply network, risk of water pollution and risk of unpredicted disaster.