The invention discloses a long-span truss construction method and a long-span truss structure. The construction method includes steps that a, preparatory workis performed, specifically, a1, supportingscaffolds are erected, a2, lateral sliding tracks are laid, and a3, longitudinal sliding tracks are laid; b, truss
assembly and lateral sliding are performed, specifically, b1, space stabilizing frames are assembled, b2, the space stabilizing frames are subjected to synchronous traction to slide, and b3, the steps b1 and b2 are repeated to form a group frame; c, jacking in position and track transition of the group frame are performed, specifically, c1, the group frame is jacked in position and then supporting legs are installed on the group frame, and c2, the group frame is placed on the longitudinal sliding tracks; and d, longitudinal sliding of the group frame and frame
assembly forming are performed, specifically, d1, the group frame is slid, d2, the group frame is jacked up and supports are
cut off and the tracks are partially slid, and then finished supports are installed on the group frame, and d3, the steps d1 and d2 are repeated, and a frame
assembly is formed.