In this paper, it is described that the uncertainty of evaluation results of Vertical Position Linearity of Analogue Oscilloscopes(VPLAO), including the courses of analysis and evaluation of uncertainty of it. Some error sources of VPLAO are discussed, including the signal amplitude errors, the reading errors of oscilloscopes, the repeatability and so on. The uncertainty of VPLAO is given out. In an example of experiment, the analysis and uncertainty evaluation results of VPLAO by using the method in this paper are presented. The courses and conclusion of analysis and uncertainty evaluation of VPLAO in this paper can be applied to the uncertainty evaluation of measurement standards of VPLAO and can also be used in the uncertainty evaluation of VPLAO itself.