Disposable income is an important factor influencing consumption expenditures. This paper mainly discusses ARIMAX model and its application in the relation between disposable income per capita and consumption expenditures. Firstly the log of disposable income and consumption expenditures of Chongqing is taken and the firstorder difference and secondorder difference sequence are drawn. The stability is judged by unit root test and is tested by cointegration test. Secondly,the ARIMAX model reflecting urban residents’ disposable income and consumption expenditures of Chongqing is set up by least square estimate. the ARIMAX model shows good performance in research on residents’ consumption effect by the fitting chart of urban residents’ consumption expenditures of Chongqing and the fitted values and the mean absolute percentage error is no more than 9.3%.