Investigation and analysis of ice core on Lake Ulansuhai from ice season of 2013 to 2014, observational parameter included ice thickness, examination of ice crystal type and bubble structure contributing to the ice cover, measurements of total nitrogen(TN), total phosphorus(TP) and chemical oxygen demand(COD_Cr). The preliminary analyses were as follows: the ice cores were divided into four layers. The two middle layers were the mainly thermal ice growth areas. The ice cover was consisted of columnar-crystal ice for the most part, and the crystal size increased with the ice-cover depth and the gas content decreased with the increase of density. The content of contaminates (TN, TP, COD_Cr)were significantly correlated with density and gas content (r_TN=0.8965, r_TP=0.8718 and r_CODCr=0.8184), and we respectively established the multiple regression equation to reveal the lake water quality characteristics in frozen period. It provides theory basis for seasonal ice-cover study and water resources planning and management in ice season.