The invention provides a vacuum heat collecting tube adopting a metal heat absorbing tube, comprising a glass outer tube (2) and a metal heat absorbing tube (5) in the glass outer tube (2), wherein the glass outer tube (2) is connected with the metal heat absorbing tube (5) through a welding joint (13) to avoid the outer end of the glass outer tube outside the metal heat absorbing tube cracking when stress is overlarge. In addition, a layer of heat-insulating material coats outside a working medium outlet tube (10) arranged in the metal heat absorbing tube (5), thereby avoiding the heat quantity of a working medium heated by the sun dispersing to a working medium flowing layer (18). Because a metal material is adopted to make the heat absorbing tube in the glass outer tube and the heat-insulating material is used for preventing the heat quantity of the working medium from dispersing to other positions, the vacuum heat collecting tube can bear high temperature and pressure, is also conveniently and directly connected to a circulating pipeline of a heat-carrying working medium and is also suitable for light-condensed moderate-temperature heat collectors.