OBJECTIVE：To pr ovide reference for the development of pharmacoeconomic budget impact analysis and related decision-making. METHODS ：Taking the incremental number of people using new intervention measures as the starting point ，a new algorithm was designed ，and the advantages and potential application scope of the new algorithm were compared with those of common algorithms. RESULTS & CONCLUSIONS ：The new algorithm directly used the sales data from the real world to calculate the number of users and their increment of each intervention scheme. Compared with common algorithms ，the new algorithm did not consider the unchanged part of the number of users of each intervention scheme ，but focused on the changing part of the number of users ，avoided the estimation of the number of the target population and the users of some intervention schemes ，and could solve the problem of unreasonable or inaccurate prediction of the target population and market share by common algorithms to a certain extent ；moreover，it could be flexibly adjusted to adapt to different market conditions and medical insurance access conditions. However ，due to the strong subjectivity of key parameters （such as preemption rate ）or inaccurate data sources ，the calculation results of the new algorithm are still uncertain.