In recent years, assessment on ground water used as water source for emergency supply was made in 17 important cities in Anhui Province. This paper put forward: selection principle of the groundwater source to be used as emergency water supply, utilization procedure and protection measures. Choosing 37 groundwater emergency as water supply source with 116.7～145.2×10⁴ m³/d. It can be supplied for 22.24～28.84 million people to maintain their basic daily life and 56.85～70.6 million to survive. The emergency water supply mechanism provides reliable guarantee of groundwater resources for cities.