To study the social consensus system under the spread of negative emotions, the nonlinear emergence model of frangibility of social consensus system is established based on Multiagent method, and effects of emotions spread frequency, opinion leaders, and shielding behavior of government on the frangibility of social consensus system are revealed. The simulation results show that the low‐frequency negative emotions spread is better than the high‐frequency one for reducing the frangibility of social consensus system. Low‐frequency negative emotions spread will lead to the group polarization, while high frequency will lead to the collapse of system. The joining of opinion leaders who are with negative emotions can promote the frangibility of social consensus system, and collapse speed of social consensus system tends to increase with the influence of opinion leaders. Shielding behavior of government cannot effectively block the spread of negative emotions. On the contrary, it will enhance the frangibility of social consensus system.