A ridging film-overlaying and sowing all-in-one machine comprises a rack. The rack is formed by a ridging trenching device, a film overlaying part, a film expansion and press mechanism, a round disc plough soil covering device and a support wheel, wherein the ridging trenching device is mounted on the front end of the rack. With the arrangements of the ridging part, the film overlaying part and the sowing part as well as a film pressing wheel, arc-shaped ridge forming work and ridge film overlaying work can be conducted during machine moving; the soil covering part on the back part can cover soil on the edge of the thin film; a seed discharging part conducts the sowing work; after the seed spreading, the seeds can be pressed by the support wheel on the rear part; the above procedures of ridging, film overlaying, sowing and pressing can be completed once for all, so farming efficiency is improved and labor is reduced; a trench pressing wheel reliably guarantees the depth of the trench not to change with a ridge surface, thereby achieving uniformed trench depth and great soil covering effect; and work cost can be reduced, plant quality and production yield can be increased, so income is added and core plant economic benefits and social benefits are enhanced.