In recent years, the regulation of double-round monopoly for super platforms has rapidly become a key instrument of the anti-monopoly practice for Internet platforms in China. This paper aims to explore the evolutionary mechanism of double-round monopoly by using evolutionary game theory and constructing a four-party evolutionary game model that includes a super platform, an incumbent platform, a startup platform, and a government regulator, based on considering the micro-dynamic interactions between subjects and the main influencing factors of the evolutionary mechanism using numerical simulation. This study illustrates that the decisions made by each subject and its probability changes affect the evolution rate of double-round monopoly. Depending on the probability of double-round monopoly in the market, government regulators need to be flexible in switching between strict and less-strict regulation strategies to evolve the system to a more desirable, stable state. As well, we conclude that the regulatory strength of the government regulator, the cross-border magnitude of the super platform, the innovation incentive subsidy of the startup platform, and the synergistic risk cost of the incumbent platform have more significant effects on the evolutionary process of double-round monopoly. Therefore, it is suggested that government regulators should focus on the cross-border magnitude of super platforms to safeguard the rights and interests of incumbent platforms and startup platforms in order to allow for fair competition. At the same time, they should also adjust the regulation intensity by the evolution of double-round monopoly in the market, in order to realize real-time dynamic regulation with the mutual coordination of multiple entities.