The invention discloses an atom generator capable of improving the atomic beam flow density. The atom generator comprises a vacuum flange, an air circuit component, a heating device and a thermal insulation cooling device, wherein the air circuit component comprises an air supply source, a vacuum micrometering valve, a gas introducing flange, an air supply pipe, a ceramic sleeve and a tungsten capillary tube; the heating device comprises a direct current stabilized power supply, an electricity introducing flange and a tungsten heater element; the thermal insulation cooling device comprises a cooling water introducing flange, a copper sleeve, a molybdenum thermal insulation layer and a cooling block; a cooling water channel is formed in the copper sleeve; a first round hole as an atomic beam outlet is formed in the lower end of the molybdenum thermal insulation layer; a second round hole as an atomic beam outlet is formed in the copper sleeve; and the axes of the tungsten capillary tube, the first round hole and the second round hole overlap with one another. In atomic angular distribution at the outlet, the atomic flow density within a small polar angle range is increased; the work efficiency of the atom generator is improved; meanwhile, the atomic flow density with a large polar angle is inhibited; and the influence on surrounding components is reduced.