Few studies have focused on the decisions of biopesticide extension agents, such as government agricultural extension agents (GAEAs) and market agricultural extension agents (MAEAs). This paper uses evolutionary game theory to construct a multi-agent biopesticide extension system model, and Matlab software is used for simulation experiments. The results show that the decisions between biopesticide extenders and adopters influence each other. The higher the initial probability of extending biopesticide in GAEA and MAEA, the faster farmers adopt biopesticide. Increasing financial funding, policy target constraints, and performance appraisal can effectively motivate GAEA to extend biopesticides. Increasing subsidies can effectively motivate MAEA to extend biopesticides. Improving farmers’ food security and environmental utilities also contributes to biopesticide extension. The findings of these simulations could provide theoretical support for the formulation of biopesticide extension policies in China.