The invention discloses a method for describing movement behavior of a luggage image based on constant dimension and variable characteristics. The method comprises the steps of performing single frame image luggage detection algorithm; combining the luggage positions in the single frame into the whole luggage image movement behavior model based on constant dimension and variable characteristics. The method has the advantages that the influence of the change of the size, color and position of the luggage image caused by activating related image processing function on the luggage movement can be overcome, the any time of the process from the luggage image appearing to disappearing can be accurately extracted and displayed through a screen; an external luggage matrix is utilized to describe the luggage positions so as to describe the luggage image movement behavior model. With the adoption of the method, the common characteristics of the same luggage in two frame images can be found out under the influence of various image processing operations on the luggage image, and therefore, the luggage image movement description is achieved.