In　South　China,　due　to　climatic　factors,　highly　weathered　granite　is　distributed　across　a　large　area　and　easily　disintegrates　after　encountering　water,　causing　many　geological　disasters　and　other　problems.　To　determine　the　disintegration　mechanism　of　highly　weathered　granite　in　South　China,　disintegration　tests　were　carried　out　on　highly　weathered　granite　in　the　Fuzhou　area　under　different　immersion　durations,　cycle　times,　and　flow　rates,　with　the　help　of　a　self-designed　disintegration　test　device.　Moreover,　the　disintegration　mechanism　of　the　highly　weathered　granite　was　revealed　using　nuclear　magnetic　resonance　(NMR)　technology.　The　results　demonstrated　an　increase　in　the　cumulative　relative　disintegration　with　prolonged　immersion　time　and　the　number　of　dry-wet　cycles.　Beyond　a　certain　flow　rate,　the　cumulative　relative　disintegration　amount　stabilized.　There　was　a　strong　correlation　between　the　steady　disintegration　rate　and　immersion　time　(or　dry-wet　cycles).　The　disintegration　process　of　the　highly　weathered　granite　was　divided　into　three　stages:　rapid,　moderate,　and　stable　disintegration.　Notably,　disintegration　primarily　occurred　around　the　large　pores.　This　study　revealed　that　the　variation　in　the　immersion　time　(or　wet-dry-scouring　cycles)　was　fundamentally　linked　to　changes　in　the　relative　volume　of　the　large　pores　in　the　rock　samples.　These　findings　provide　valuable　insights　for　predicting　and　mitigating　surface　disasters　on　highly　weathered　granite　slopes.