The invention provides a bobbin thread remaining length calculation method for a sewing machine. The method includes steps: acquiring bobbin thread winding length A in winding of a thread on a bobbin;enabling a controller of the sewing machine to acquire bobbin thread initial length L of the bobbin thread on the bobbin, wherein the bobbin thread initial length L refers to the bobbin thread winding length A or bobbin thread remaining length after finishing of last sewing; starting stitching; after sewing is finished, enabling the controller of the sewing machine to acquire a stitch number M and a bobbin thread utilization length B in each stitch pitch, and enabling the controller of the sewing machine to automatically calculate the bobbin thread remaining length Y, wherein Y=f(L, M, B), and f(L, M, B) is pre-stored in the controller of the sewing machine. By adoption of the method, the remaining length Y of the bobbin thread on the bobbin can be calculated effectively, and accordinglythe bobbin thread remaining length can be effectively monitored; especially, bobbin structural modification is avoided, the method can be implemented by adoption of a normal bobbin, exclusiveness of the bobbin is avoided, universality of the bobbin is realized, and processing difficulty of the bobbin is lowered.