Abstract: There exist two main categories of attitude determination approach using globalpositioning systems.The first is based on a single baseline observation model,which choosesbaseline and ambiguity as its parameters.Firstly,the baseline coordinates were estimated inagiven frame.Then,in alliance with the corresponding baseline coordinates in the rigid bodyframe,the attitude was estimated.The second category is based on mutibaseline observationmodel,which takes ambiguity and attitude matrix as its parameters,and solves the ambigui-ty and attitude matrix simultaneously.The CLAMBDA method and MC-LAMBDA methodwere choosen as the representative algorithms of these two categories of approaches,andthey are described in detail,then a comparation and analysis between them were presentedwith numerical examples.