Abstract:When calculating resources / reserves by using parallel section method, if the block of the ore body has an area in both adjacent sections, and engineering interval which controls two area of the project and the average thickness of the project which controls each section are not equal, or two adjacent section areas do not have the similar shape, if using the prism formula to calculate the block volume, there will be some errors. While the quasi column formula is a general formula for calculating the volume of the block. It is not limited by the above conditions. So, In this case, it is suggested that the prism and truncated cone formula should be stopped using, while quasi column formula should be widely used to calculate the block volume of the ore body.