In many social scenarios, individuals tend to change their opinions due to conformity behavior. To investigate the impact of conformity behavior on the evolution of individual opinions, this paper proposes a modified Hegselmann-Krause(HK) model with group pressure. Unlike the existing model, the weights of individuals influenced by their neighbors are not always the same. Thus, the convergence properties of this model are theoretically analyzed, and the model's convergence time, as well as its relationship with confidence bound and group pressure, are given. Considering both cooperative and antagonistic relationships in groups, this paper further proposes a modified signed HK model with group pressure and proves its convergence. This model's convergence time is also given, as well as its relationship with confidence bound and group pressure, are also given. Finally, simulations are given to study the effect of confidence bound and group pressure on the evolution of opinion and the convergence time of the proposed two models. The validity of the two proposed models is also verified. The results show that the higher the confidence bound and group pressure, the faster the convergence of individual opinions in groups.