The invention discloses a generator set driven by an engine. The generator set comprises a sound proof box, an engine, a generator and an exhaust
muffler, wherein the sound proof box is composed of an upper cover, side walls and a
chassis; the engine is arranged on the
chassis, and an engine cooling fan is arranged at the side inlet of the engine and guides cooling air into the engine; a cooling fan is arranged at the connection part of the generator and the engine to guide the cooling air into the generator; the exhaust
muffler is arranged at the rear side of the generator and parallel to the axis of the generator; one end of the exhaust
muffler is connected with the engine through an
exhaust pipe; a hot air exhaust chamber is further arranged in the sound proof box, is composed of a side panel, a cover plate and an engine speed regulation base, and encircles an engine cylinder end, a cylinder body and one part of the
exhaust pipe; an opening is formed in the rear side of the hot air exhaust chamber and is connected with a first ventilation hole at the side wall of the sound proof box. According to the generator set, the problems of
noise and
heat balance can be effectively solved, and the
oil temperature of the engine can be obviously reduced beyond 30 degrees centigrade, thereby ensuring that reliable
lubrication of the engine and the
power level of the complete generator bring into correspondence with open-shelf products.