As the most promising plasma facing materials (PFMs),potassium doped tungsten alloy have exhibited excellent high temperature mechanical properties. In order to evaluate the hydrogen isotope residence in WK alloy,the pure W and the WK alloy with 82 ppm potassium doping were prepared by spark plasma sintering(SPS). After deuterium was introduced into potassium doped tungsten alloy by gas-phase thermal charge, thermal desorption spectra(TDS) were obtained with different heating rates. The results show that deuterium released gradually at 600 K～1200 K. And after doping K, the activation energy of thermal desorption of deuterium reduced from 0.86 eV to 0.68 eV; The retention of deuterium in tungsten sample is less than 1 appm and it is enhanced with doping K,but still lower than that of commercial pure W