The　solar　power　tower　system　is　an　attractive　method　for　electrical　power　generation　on　a　large-scale,　and　offers　significant　performance　advantages　over　line-focus　systems.　The　tracking　control　of　heliostats　is　one　of　key　technologies　of　power　tower　system.　Firstly,　this　paper　presents　the　formulae　of　tracking　angle　and　incidence　angle　of　heliostats　based　on　position　in　mirror　field　by　vector　analysis,　which　can　be　made　use　of　optical　efficiency　analysis　such　as　cosine　factor　and　shading　and　blocking　factor.　Then,　the　changing　trend　and　speed　of　heliostats＇　tracking　angle　was　analyzed,　furthermore,　which　is　convenient　for　customizing　tracking　strategy　and　designing　mechanical　structure　of　heliostats.　Finally,　statistical　analysis　of　heliostat　tracking　angle　error　as　a　result　of　tracking　controller＇　longitude　and　latitude　setting　error　was　done,　which　can　be　used　of　determining　control　region.