Pedzisa mutsara unotevera: Nokuda kweMitambo yeOlympic yeZhizha ya2012, Zuva raifungidzirwa kuti rinodiwa mumamita 400 uye
1500 metres freestyle, pamwe chete nomukwikwidzi mumakwikwi e200 metres freestyle. Muchiitiko chake chekutanga, mamita mazana mana akasununguka, akahwina menduru yegoridhe nenguva ye3: 40.14, achiputsa rekodhi yeOlympic yaimbove naIan Thorpe uye achiva mutambi wekutanga wechirume weChinese kuhwina menduru yegoridhe kumaOlympics. Nguva yake yakanga iriwo yechitatu yakakurumidza munhau, 0.07 masekondi kure nenhoroondo yenyika, uye kuisa rekodhi idzva reAsia. Pashure pezuva rose rokupora, Sun akakwikwidza mumakwikwi emamita 200 akasununguka. Akakunda menduru yesirivha mumutambo wokupedzisira, achibatanidza naPark Tae-hwan nenguva ye1:44.93, rekodhi itsva yenyika. Zuva rakatevera, Sun akahwina gumbo reanchor mumakwikwi e4 × 200 metres freestyle relay kubatsira timu yeChinese kuhwina bronze, menduru yekutanga yeChina yeOlympic mumutambo wevarume relay.