The invention discloses an ion source, and the ion source comprises a support assembly, a grid mesh assembly, and a discharge assembly. The interior of the support assembly is provided with a cavity, and the grid mesh assembly is disposed at one end of the support assembly. The other end of the support assembly is opened. The discharge assembly is slidingly disposed in the internal cavity of the support assembly, and is fixedly connected with the opened end of the support assembly. The ion source is simple in structure, is convenient to disassemble, and is high in detection efficiency.