Sanshandao gold mine is located in the Laizhou Bay， eastern China.Its north and west sides are bordering the Bohai sea， only the southeast side is connected to the land.The mining operations are below the sea level， so the sea water is the potential threat to the mine.In order to predict and prevent water inrush disaster， it is important to identify the mine water source and determine the mixing ratios.In view of the identification of water source in mine tunnel， domestic and foreign scholars have done a lot of research.At present， the methods of mine water source identification are neuron network method， based on entropy weight-fuzzy variable set theory， clustering analysis， distance discriminant analysis and Fisher discriminant method.These methods can make a good distinction for water with simple composition， and are only qualitative identification for the composition of the complex water source， and there is no quantitative determination of mixing ratios of the mine water.Based on hydrogeochemical and isotopic analysis， the method of principal component analysis （PCA） was used to identify the mine water sources （seawater， 375-20 Mg， freshwater and 320-7 Ca） of Sanshandao gold mine and established the mixing model of mine water.The 375-20 （Mg） and 320-7 （Ca） are both brine but have different hydrochemical characteristics.The 375-20 is rich in Mg and the 320-7 is rich in Ca.The first， the second and the third components of the PCA method explained 88% of the information of the water samples， so the water sample can be represented by these three principal components.The end-members mixing ratios were calculated by the maximum likelihood method and the evolution rules of mine water were analyzed according to the calculation results.Unlike the traditional method， the maximum likelihood method holds that the end-member concentration is not a fixed value， but a change in time and space， and the influence of mining on the end-member can be effectively reflected by this method.The research shows that the method can effectively identify the water sources and calculated the mixing ratios.The seawater is the main component of mixed water and for the entire mine the proportion of the seawater fluctuated around 50% every year， the proportion of 375-20（Mg） and freshwater fluctuated around 20% and the 320-7（Ca） flucated around 10%. At -510 m sublevel， the mine water has a high proportion of seawater. At most of the water sites which are located between the prospecting lines 1660 and 2230，the proportion of seawater are more than 50%， especially at 510-2， the highest proportion is 77%. The main range affected by fresh water is 465 m sublevel and above. F3 fault is greatly affected by the mining， and the proportion of seawater of sites around which fluctuate greatly， so the monitoring of F3 fault needs to be strengthened.