As　the　natural　barrier　of　the　high-level　radioactive　waste　(HLW)　disposal　project,　the　host　rock　is　essential　to　ensure　the　stability　and　safety　of　the　project　in　long-term.　With　the　purpose　to　establish　an　effective　method　for　evaluating　the　rock　quality　for　site　characterisation,　the　relation　between　the　average　structure　spacing　D,　which　is　used　as　a　quantitative　index　to　describe　the　fracture　distribution　of　rock　mass,　and　the　scores　of　relative　metabolic　rate　(RMR)　system　is　set　up.　It　is　shown　that　the　point　set,　which　is　composed　of　the　values　of　RMR　and　D,　has　a　fan-shaped　positive　correlation.　The　value　of　D　increases　with　the　score　of　RMR.　Moreover,　the　index　of　structure　spacing　D　in　lower　order　area　shows　a　better　corresponding　relation　with　its　rock　mass　quality　than　in　higher　order　area.　The　method　is　used　in　the　evaluation　of　rock　mass　quality　around　the　borehole　BS16　in　Beishan　area;　and　a　good　accordance　between　the　distribution　of　D　and　RMR　is　obtained.　The　results　suggest　that　it　can　be　used　as　an　effective　and　alternative　approach　of　rock　quality　evaluation　in　the　site　characterization　of　HLW　disposal　project.