The invention relates to a dynamic reserves calculation method and apparatus. The method comprises the steps of determining a unit pressure drop gas yield formula of a target region; drawing a unit casing pressure drop gas yield curve by utilizing a mutual relationship between a unit pressure drop gas yield and a unit casing pressure drop gas yield according to the unit pressure drop gas yield formula; judging whether reserves of the target region already reach an overall employment stage or not by utilizing the unit casing pressure drop gas yield curve; and performing calculation on dynamic reserves, already reaching the overall employment stage, of the target region and dynamic reserves, not reaching the overall employment stage, of the target region. According to the technical scheme, the practical test effect of the dynamic reserves calculated according to the unit casing pressure drop gas yield curve is relatively good, an error is in an acceptable range, and especially for a gas field with relatively long production time, a result is more reliable.