In this paper,it is described that the uncertainty of evaluation results of linearity of linear measurement system by using the least mean square method,including the courses of analysis and evaluation of uncertainty of it.Some error sources of linearity evaluation are discussed.Several main methods to decrease the linearity evaluation errors and evaluation uncertainty have been proposed.They are environment influence controlling,and decreasing the signal uncertainty to decrease the evaluation uncertainty caused by signal source.Through the practical example of experiment,the analysis and uncertainty evaluation results of linearity are presented in this paper,The courses and conclusion of analysis and uncertainty evaluation of linearity in this paper,can be applied to the uncertainty evaluation of masurement standards of linearity,can also be used in the uncertainty evaluation of linearity itself.