Considering the problem of Field-of-View (FOV) constraint in the precision guidance mission，an Impact Time Control Guidance (ITCG) law based on look-angle shaping is proposed. Firstly，a cubic polynomial reference look-angle profile with respect to the non-dimensional relative range is constructed. The impact time and maximum look-angle are expressed as equations of the profile parameter，and the reference look-angle profile satisfying the constraints is obtained by solving the parameter. Based on the dynamic model of the missile，the guidance command of tracking the reference look-angle profile is designed，the ITCG law with FOV constraint is obtained，and the achievable range of the impact time is derived. The proposed guidance law does not depend on the time-to-go estimation，linearization model and switching logic，and the terminal zero control can be achieved. Finally，the digital simulation results verify the effectiveness of the proposed guidance law.