The invention relates to a longitudinal sealing structure of a filling machine for longitudinally sealing continuously transferred sheets as a paper tube. The longitudinal sealing structure of the filling machine comprises a heating part, a pressing part and a paper tube forming roller, wherein the heating part is used for inductively heating the bonded edges of the paper tube to be formed; the pressing part is used for pressing the bonded edges; the pressing part and the heating part are respectively positioned at the inner and outer sides of the paper tube to be formed; the paper tube forming roller is used for guiding the paper tube to be formed to form a formed tube structure along a set trajectory, and comprises at least one set of forming rollers; the at least one set of forming rollers is near the lower parts of the heating part and the pressing part; the heating part, the pressing part and the at least one set of forming rollers are positioned on a base; and the base is driven by a driving mechanism to reciprocate in a section of distance in the basic tendency of the paper tube.