Mass spectrum ionization source of vacuum ultraviolet lamp with no light window

The invention discloses a mass spectrum ionization source of a vacuum ultraviolet lamp with no light window. The mass spectrum ionization source of the vacuum ultraviolet lamp with no light window comprises the vacuum ultraviolet lamp with no window, a primary difference voltage stabilizing cavity, a secondary difference voltage stabilizing cavity, an ultraviolet light incidence channel, an electrode slice group generating a uniform electric field, a sample inlet and an ion lead-out electrode plate. Gas pressure inside the primary difference cavity and gas pressure inside the secondary difference cavity are controlled by two baffle valves respectively, and the gas pressure values are measured by a vacuum gauge. When the mass spectrum ionization source of the vacuum ultraviolet lamp with no light window works, the gas pressure of the primary difference cavity keeps higher than that of the secondary difference cavity so as to avoid the problem that sample gas inside the secondary difference cavity enters the primary difference cavity to cause impure electro-discharge gas, and stable work of the vacuum ultraviolet lamp is ensured. Ultraviolet light emitted by the vacuum ultraviolet lamp passes through the incidence channel to ionize the sample gas inside the secondary difference cavity.