The ultimatum game (UG) is a well-studied game used extensively by behavioral economists or psychologists to study people’s fair decision-making. In this game, two players are given an opportunity to split a sum of money. One player (i.e., the proposer) decides how to divide up the money between him- or herself and another player (i.e., the responder). If the responder accepts, the split takes place as proposed; however, if the responder rejects, neither of the two individuals receives any money. Game theory predicts that the proposer will offer the smallest amount and that the responder will accept it. However, once again, this prediction is at odds with observed behavior across a wide range of societies. With the rise of UG, the individual and cultural differences in UG enter into the eye of researchers gradually. Thus current paper gives a review about those differences. Based on this review, several suggestions regarding to the direction for future research are given. So far, the researches on age differences consistently found an age-related change in UG. Specifically, some researches show that the older children offer more than the younger groups as proposer. And the relationship between age and rejection is positive. Those findings are mostly explained with reference to theories of socialisation and the development of the ability of impulse control. Then, in the gender differences the current results agree on some findings: there is little overall difference in the mean offers between men and women, while women are more likely to reject. The current studies attribute the gender differences to the contributions of cultural factors and biological differences between men and women. Next, there are fruitful researches about the differences of psychological characteristics. The first aspect is emotional control. The second aspect is Social Value Orientation. Current paper also gives a review about the need for cognition as well as personality. Finally, the experiments during the last 20 years demonstrate that decision-making may be heavily influenced by cultural differences. The behavior in the UG is systematically related to the continents in which the experiment was conducted. In details, the rejection in Asian is highest, and participants in eastern are more prone to fair outcomes. The UG results between agricultural society and industrial society are substantially different. And there is also a difference in the mixed-race groups. While recent studies have shed light on the existing differences in UG, less is known about the mechanism behind the behavioral differences. In order to get a full understanding of the UG, further research is expected to integrate existing findings and related theories. In addition, further research could link all sorts of differences to the specific biochemical or neural mechanism, which can contribute to a deeper understanding of the behavioral differences in UG at the level of molecular genetics and neuropsychology. How to improve the UG paradigm and how to deal with the money effect also have brought challenge and expectation for future researchers.