The invention discloses a steam generator and a steam cleaner with the steam generator. The steam generator comprises a boiler main body and a boiler outer shell; the boiler main body comprises a connecting plate and a heating ring; a first vaporization cavity is formed between the inner wall of the heating ring and the bottom of the boiler outer shell; a second vaporization cavity is formed between the outer wall of the heating ring and the boiler outer shell; the connecting plate is provided with an exhaust pipe and a water inlet pipe; multiple annular grooves are formed in the outer wall ofthe heating ring; circulating grooves are formed in the annular grooves; the circulating grooves of the adjacent annular grooves are formed in two opposite sides of the heating ring; and a communicating hole is formed in the tail end of the heating ring. The steam generator has the following advantages and effects: through secondary utilization of the outer side and inner side space of the heating ring, the heat utilization rate of an electric heating pipe is improved; and through lengthening of circulating paths of liquid-state water in the first vaporization cavity and the second vaporization cavity, the contact area and the contact time of the liquid-state water with equipment are increased, so that the vaporization efficiency of the generator is effectively improved, and the completevaporization is realized.