Abstract: The authors choose two types of waters of which one is mining subsidence lake and another is a general lake which are not affected by mining,to study the environment conditions of Chrysophyta and Xanthophyta growing with comparative analysis method.The reasons for Chrysophyta and Xanthophyta seldom growing in the water of mining subsidence area are low transparence and high degree of mineralization,and much more content of Fe²⁺ and sulphide in the mine drainage,much more content of organic and ammonia-nitrogen in the domestic sewage drained to mining subsidence area by monitoring during the four seasons of a year.The study achievements have provided a reference for us using biological method to appraise the ecological condition of mining subsidence area.