Etching　anisotropy　of　GaP　relies　on　the　etching　parameters　and　the　shape　of　the　mask,　yet　it　is　very　difficult　to　obtain　the　repeatable　mask　shape.　In　this　paper　a　method　to　control　the　surface　profile　by　changing　the　parameters　of　inductively　coupled　plasma　(ICP)　machine　itself　rather　than　depending　on　the　indefinite　mask　shape　was　studied.　It　is　concluded　that　cathode　RF-power　and　chamber　pressure　are　the　two　main　parameters　in　the　surface　profile　control.　The　smaller　the　RF-power　is,　the　bigger　the　etching　angle　obtained;　the　higher　the　chamber　pressure　is,　the　bigger　the　etching　angle　achieved.　BCl3　plasma　chemistry　is　generally　used　to　etch　GaP　compound　semiconductors　in　a　planar　ICP　reactor,　into　which　the　Ar　plasma　chemistry　was　added　in　this　study　to　allow　the　plasma　to　maintain　high　ion　density　conditions　over　a　broader　range　of　operating　pressure.