The utility model relates to a roof truss node gusset plate and a lightweight steel structure thereof, wherein the plate body of the roof truss node gusset plate is formed by punching a metal thin-wall plate and comprises a plate type integral connecting piece comprising a chord member connecting plate and a web member connecting plate; a punched pressing rib protruding towards the front surface of the metal thin-wall plate and not communicated with the edge of the plate body is arranged on the plate body; the punched pressing rib is composed of a transverse punched pressing rib, a left vertical punched pressing rib, a right vertical punched pressing rib, an upper arched punched pressing rib and a lower arched punched pressing rib; the transverse punched pressing rib is arranged on the chord member connecting plate; the left vertical punched pressing rib is distributed from the chord member connecting plate and the web member connecting plate; and the right vertical punched pressing rib is distributed from the chord member connecting plate and the web member connecting plate. According to the utility model, the bearing capacities and the rigidities of the connecting plates are greatly increased; therefore, the connecting plates become more firm; in particular, in the event of being stressed by force in a plurality of directions, the connecting plates are difficult to bend or deform.