Water resources vulnerability is an important measurement of water security and the basis of regional sustainable development. Taking Henan Province and its 18 cities as evaluation unit, the index system of water resources vulnerability evaluation was established by considering three subsystems of natural condition, social economy as well as water supply and consumption. Entropy Weight Method and Linear Weighting Method were used to calculate water resources vulnerability of typical dry year. The water resources subsystem index and vulnerability index were investigated from city, region to the entire province. The Contribution Model was applied to identify the principal contribution factors of water resources vulnerability in order to provide a scientific basis for water resources management in Henan Province. The results show that the subsystem indexes range from water resources natural condition index, water resources supply and consumption index, to water resources socio-economic index. And there exists a certain difference in water resources subsystem index and vulnerability index at different levels of urban cities, regions, and province with the both indexes increasing from southwest to northeast. The water resources vulnerability for the entire Henan Province is classified as Grade Ⅲ, which is medium vulnerability. The contribution of the three sub-systems to water resources, vulnerability for the main cities and the whole province follows a same rank order from natural condition, water supply and consumption condition, to social economic condition. The four indicators of the natural condition sub-system are principal contribution factors to water vulnerability. The per-mu chemical fertilizer conversion scalar in the socio-economic subsystem and the per-capita comprehensive water consumption and per-mu irrigation water consumption in the water-supply-consumption subsystem are also major contribution factors to water resources vulnerability. The three subsystems should take “multi-channel water supply, improving the capacity of water supply”,“rationally expanding cities and towns, optimizing population and economic structure, improving urban living and production level”,“improving water utilization efficiency, saving water”as the breakthrough points to achieve accurate “vulnerability reduction”, so as to guide the sustainable development of water resources.