The spread of public opinion across the Internet in China was proposed by constructing a two-player symmetric evolutionary game model with incomplete information, since most of the players have limited knowledge about the spread and exact nature of public opinion. The two-player symmetric game model was presented to decide the strategic choice of players, and the replicated dynamic equation was built to explain the evolution directions of different strategic groups. The memory length of players, updates views and memory list were introduced according to the interaction rules. The simulation result shows that it is easy for players to follow trends under such circumstances, leading to herd behavior and a world in which most players adopt the same view. Furthermore, herd behavior is affected by a series of factors: most notably analysis-strategy based interactive interests, cost coefficients, and memory length. This research offers insights for practical application on how to analyze and guide the spread of public opinion on the internet.