On the subject of what affect voters¡¦ vote choice, political scientists for a long time emphasize three answers: party identification, candidate orientation, and issue orientation. About issue orientation, Rational Choice Theory assumes that human are rational pursuing maximizing self- interests. When voters are making their vote decisions, they would observe the issues positions of competing parties or candidates, comparing with their own positions, and then vote the party or the candidate who can represent their own positions best. Spatial Theory, from Rational Choice Theory, takes those abstract issue positions into some issue space. Both the issue positions of voters and parties could be presented by some points in the space, and the length and direction between the points can represent the differences between issue positions. There are several different models in Spatial Theory, and different models advocate different ways about how voters use the points in issue space to form their evaluations to competing parties or candidates. In this paper, we take the viewpoints of Spatial Theory to research the issue voting behavior of Taiwanese voters. First, we try to know the spatial distribution of voters¡¦ issue positions. Then we inspect the association between voters¡¦ social back- ground elements and issue position. Finally, we test three models of Spatial Theory, proximity model, directional model, and RM mixed model, to know how Taiwanese voters use issue positions to form their party-evaluation.