Abstract: Mineral land reserve is a kind of mineral resource reserve, which is an important measure to ensure the security of the country's medium and long-term mineral resources supply.And the calculation of reserve scale is the most important part of the study on mineral land reserve.Taking demand and supply as the entry point, this study explores a simple and operable method for the calculation of mineral land reserve scale.The basic principles of mineral land reserve are clarified as protecting the safety of resources, insisting on appropriate reserves, treating minerals differently and adjusting the scale dynamically.And the influencing factors are mineral resource situation, reserve type, domestic resource supply, and the affordance of overseas resource.During the calculation of reserve scale, it is necessary to distinguish superior minerals from those in short supply, and set the scenarios for strategic reserve, protective reserve and advantageous reserve according to the functions of mineral land reserve, so as to determine the corresponding calculation methods.In addition, batch reserve is suggested in actual work.The purchase and storage scale in each period should be determined flexibly according to the mineral resources and economic development to gradually reach the ideal reserve scale.