From a certain point of view, the incentive principle is like the catalyst in the chemical experiment, according to the specific circumstances to determine the use of time. In the practice of human resource management, there is not a kind of absolutely effective and suitable incentive opportunity, and the choice of incentive opportunity is random. In human resource management, we should flexibly choose the time of incentive or adopt the form of comprehensive incentive according to the concrete objective conditions, so as to play the role of incentive effectively. The motivation principle carries on in the different time, its function and the effect have the very big difference. According to the difference of time, the incentive opportunity is divided into timely incentive and delayed incentive. According to the time interval, it can be divided into regular incentive and irregular incentive, and according to the working cycle, it can be divided into pre-period incentive, mid-period incentive and end-period incentive