The exponential construction form of the traditional grey prediction model with single variable restricts its simulative and predictive abilities for the oscillation sequence with poor samples. Therefore, an oscillation sequence is expanded to an interval grey number sequence with the defined upper and lower bounds through envelope lines, which restores the interval grey number form of oscillation sequence under the condition of uncertain influence factors. After this, the value ranges of oscillation sequence are simulated and forecasted by using the modeling method of forecasting interval grey number. Finally, the proposed method is employed to effectively simulate the change laws of Chongqing air quality index(AQI). The study results provide a novel analysis method and modeling tool for the oscillation sequence with poor samples.