Open innovation crowdsourcing can help enterprises meet the challenges of a rapidly changing environment and improve their innovation performance. This study introduces network externalities as influencing factors of the crowdsourcing open innovation synergy mechanism. This study constructed the game payment matrix of the crowdsourcing open innovation synergy mechanism, and the evolutionary game method obtained the equilibrium solution of the crowdsourcing open innovation synergy mechanism. The impact of changes in the main influencing factors on the issuers' and receivers’ willingness to collaborate and innovate was explored through numerical and case studies. The study shows that the higher the synergy benefit and its allocation coefficient need to be within a reasonable range for the willingness to collaborate and innovate to increase; the lower the original cost of both parties, and the higher the cost reduction coefficient under the policy support of the crowdsourcing platform, the higher the willingness to collaborate and innovate; the higher the network externality and the lower the penalty for breach of contract, the higher the desire to collaborate and innovate. The study recommends strengthening non-school education to guide innovation for all, and refining relevant policies to tailor innovation to local conditions. This study provides a new perspective and theoretical guidance for enterprises to build a crowdsourcing open innovation synergy mechanism and is a valuable reference for open innovation management.