Under the current inter-provincial tie-line power assessment mechanism in China, regional power grids typically return assessment fees to each province based on their relative tie-line and frequency control performance. However, under this return method, if all provinces in a regional grid perform poorly in frequency regulation capacity, the returned control performance standard (CPS) fines for each province will be close, resulting in a lower penalty for power and frequency over-limit violations on provincial grid interconnections. To simulate and compare the decision-making of provincial dispatch and control centers regarding automatic generation control (AGC) adjustable capacity under different CPS assessment fee return methods, this article proposes a two-province game model. In this model, the two provinces follow best response dynamics for alternating frequency regulation simulation and scheduling optimization until a balance is reached or the variation in reserve capacity is within a certain range. Testing different combinations of assessment prices and return methods, the results show that determining and announcing the provinces to receive fine returns based on their ranking in assessed electricity quantity can better motivate provinces to improve frequency regulation performance.