The probability analysis of dynamic distribution of beam positioning in high power laser facility is added to traditional stability design, and a stability analysis method based on dynamic distribution is proposed. Taking spatial filter in large laser facility as object, we discuss how to optimize its structural parameters by this method, with its optical parameters being constant. This method is aiming to constraint the relative stability of components in spatial filter, and it is different from the traditional method which is focused on the absolute stability of single components. Together with the traditional method, optimization can be achieved in dynamic range and distribution pattern of the beam at the same time, and a stable and reliable structure will be provided for facility operation.