Time trade off(TTO) is one of the most common methods used to measure health utility , which is widely applied in developing EQ-5D value sets and calculating QALYs. Traditional TTO has some limitations in the valuation of health states considered worse than dead. Therefore, a series of new TTO approaches have been developed. We introduced and compared the application of different time trade off methods in health utility studies. The use of a specific TTO method should be chosen by research objects. A further exploration of TTO needs to be conducted.