This research attempts to find out the possible reasons which affect to the polling supports of pan-blue and pan-green¡¦s presidential candidates by first-order autoregressive model since May 20th 2000 to March 22nd 2008. We explore the effect of these factors and how the factors to affect the degree of both candidates¡¦ supports. We try to explain the fluctuating of both sides¡¦ degree. To exploring the change of the polling supports and degree, this research collects many significant events during the said period. We view the degree of each category¡¦s effect by sorting out government¡¦s policy, economy, ideologies of independence and unification, the personal issues of candidates, parties¡¦ issue and others to explain the reasons of polling supports¡¦ change in addition I add the effect of media organ, candidates nominating or not, the difference of each election, and the time effect. From the results of this research, the effect of media positions for polling outcomes is not significant, but the candidates nominating or not and the difference of each election affect to pan-blue¡¦s supports and both sides¡¦ degree. Besides, the issue of ideologies of independence and unification influences to pan-blue and pan-green¡¦s candidates, but the candidates personal issues affects the change of the both sides¡¦ degree. When the events of government policy and ideologies of independence and unification are happened more nearly at the polling time, the effect to the change of the polling supports will be greater.