Abstract: The conventional aerological data are filtered using two filtering methods to detach meso-scale or sub-weather scale systems in this paper.The first method is reproduced from the operator designed by Shapiro (1970) and Xia Dai-Qing et al. (1983). The second method is reproduced from the filtering operator designed by Barnes and the experiment is carried out by means of different weight function constants.The analyses show that systems can be detached by either of the two methods. Eqs.(14)of the larger weight function constant is superior to others in view of the effect of the scalar separation; and Eqs. (1) and (14) of the smaller weight function constant are the Second. It is also shown that there is a close relationship between the low-level meso-scale systems and strong convective weather(such as heavy rainstorms), which are often located between meso-scale cyclones and anticyclones,being closer to meso-scale anticyclones.