The utility model relates to a line spacing regulating mechanism of a double-line sugarcane planter. The line spacing adjusting mechanism comprises a rack, wherein line spacing adjusting frames are symmetrically arranged on left and right sides of the lower side of the rack, front and back ends of the line spacing adjusting frames are connected with connecting plates installed at front and back ends of the lower side of the rack respectively, lead screw adjusters are arranged on left and right sides of the rack respectively, each lead screw adjuster comprises a lead screw sleeve fixedly installed on the rack, an adjusting lead screw is arranged in each lead screw sleeve, a moving sleeve is arranged between each adjusting lead screw and each lead screw sleeve, an inner thread is arranged in each moving sleeve and matched with an outer thread of each adjusting lead screw, a hand wheel is arranged at the outer end of each adjusting lead screw, the outer end of each moving sleeve is connected with a fixed plate on each line spacing adjusting frame through a fastening joint, a guide groove is axially formed outside each moving sleeve, a guide key is arranged on each lead screw sleeve and located in each guide groove, and a furrow opener fixing base is arranged on each line spacing adjusting frame. The line spacing regulating mechanism is simple in structure and accurate, rapid and easy in line spacing adjustment, so that the working efficiency is greatly improved.