Fairness preference model can better explain such mutual-benefit phenomenon asgood-for-good, but ignored is such an important basic issue of whether the cardinal point of the fair comparison satisfies the fairness or not. Through modifying the basic fairness preference, this paper constructs a double factor income fairness preference model which overcomes the problem of lack of basic assumptions in the original model. The paper comes to a conclusion that double factors are inversely changing, and that doubl...