Abstract: Due to the complex distribution and fluid properties of the fractured-cavernous carbonate reservoir,it is difficult to precisely evaluate the reserves.As a result,no economic and effective development plan has been made so far.This paper discusses the current static reserves calculating method and develops a new dynamic reserves calculating method,which is more available to be applied to calculate the reserves in fracture-cavernous carbonate reservoirs.Taking Tahe Oilfield as an example,this paper mentions that the non-uniform distributed fractured caves cannot be exactly described and some geological parameters cannot be acquired based on the current reserves calculating reserves method,which results in the big errors of the reserves calculating results.Therefore,on the basis of the mass balance theory,this paper introduces a new dynamic method,which has no special requirements for the concrete forms and distribution of fractured caves and can analyze and evaluate the reserves of fractured-cavernous carbonate reservoirs more precisely without requiring too many parameters.The new method has been applied to actual oil reservoirs,proving that it is credible and accurate.It is of theoretical and practical significance to the development of similar reservoirs.