The invention discloses a fuel supply system for a gasoline engine. The fuel supply system comprises an oil tank, a liquid level sensor is arranged on the inner surface of the oil tank, an oil tank cover and an oil level gauge are arranged on the outer surface of the upper end of the oil tank, the outer surface of one end of the oil tank is fixedly connected with a first oil duct, a gasoline filter is arranged on the outer surface of one end of the first oil duct, an oil inlet pipe is arranged on the outer surface of one end of the gasoline filter, an oil outlet pipe is arranged on the outer surface of the other end of the gasoline filter, an oil cavity is formed in the gasoline filter, and a buffer cavity is formed in the outer surface of the upper end of the oil cavity. The fuel supply system for the gasoline engine is provided with a buffer cavity, an electrostatic eliminator and an activated carbon screen, the contact area of gasoline and a filter screen can be increased, filteringis accelerated, electrostatic ions existing on a carburetor can be eliminated, air filtering strength can be enhanced, and a better use prospect is brought.