The x-ray spectra of hollow atoms in the interaction of highly charged argon ions with beryllium solid surface are reported. The interaction ions, provided by t he electron cyclotron resonance (ECR) ion source in the National Laboratory of t he Heavy Ion Research Facility in Lanzhou(HIRFL), include bare argon ions, which are produced by the ion source for the first time, and hydrogen-like, helium-li ke and lithium-like argon ions. We found that the K-shell x-ray yield of single particles in the interaction of hydrogen-like argon ions is 36×10-3, wh ich is 5 orders more than that of helium-like argon ions, and the K-shell x-ray cannot be measured in the interaction of lithium-like argon ions with beryllium surface.