In this paper, the model of opinion evolution is put forward to study the influence of individual knowledge learning on the stability of opinion and convergence time in group decisionmaking. The simulation result shows that the level of knowledge of the individual decisionmaker, the number of the neighboring nodes and the rate of knowledge learning have a positive effect on the stability and convergence time of opinion, in which the level of knowledge of the individual decisionmaker has the most significant on them. At the same time, the steady state of group opinion is uncertain. The simulation example shows that the dynamic opinion evolution model can be applied to public decisionmaking, and can provide the research basis for the analysis of the influence on opinion evolution and convergence time in dynamic group decision making.