Abstract: Person-fit research which based on Guttman model, Item response theory and Nonparametric Item Response Theory is a new kind of method to discriminate the aberrant responses behaviors in psychological tests. Traditional person-fit statistics were used to discriminate the abroad aberrant behaviors but current person-fit researches are more special and visual. The researches of specialized statistics, graph and regression analysis have become the focus of current study. However, all kind of person-fit statistics are influenced by many irrelevant factors. How to control these factors and improve the practical value of person-fit statistics will become the main research tendency in this area

Key words: Psychological tests, person-fit, IRT