This paper studies the optimal investment, consumption and annuitization time post retirement for the retirees with mortality risk and bequest utility. According to the subjective mortality probability at retirement, the retirees are divided into two main groups: the first group cannot live up to the maximum annuitization time with probability one; the second group can live up to the maximum annuitization time with a certain probability. Since retirement, the retirees need to determine the investment and consumption until the death time or the annuitization time. The optimal annuitization time is set to be the time that maximizes the sum of the accumulated expected consumption utilities before and after purchasing an annuity and the expected bequest utility. By adopting the power utility, this paper obtains the closed-form optimal investment-consumption strategy and the conditions under which the first group of the retirees do not buy the annuity throughout the lifetime and the second group buy the annuity at the maximum annuitization time. Finally, numerical analysis is provided to analyze the effects of gender, the survival period, the bequest utility, the discount function, the risk aversion, the financial environment and the annuity price on the annuitization behaviors of the retirees.