For polar ship operating in ice-covered areas, numerical prediction and relevant research on maneuverability are particularly important. In this paper, a numerical method considering circumferential crack fracture of level ice based on former research is applied to calculate ice load and predict motion of ship turning in level ice. The difference between bending failure and crushing failure are also taken into consideration during the turning simulation, meanwhile crushing failure pattern is validated with measured data. The turning performance of icebreaker AHTS/IB Tor Viking Ⅱ based on present method is analyzed and compared with full scale measurement. The simulated icebreaking capability of the ship is also validated with sea trials and previous work. The results show that good agreement is achieved and the accuracy of the numerical prediction is improved by including crushing failure into previous research.