Chaenomeles speciosafruit is a traditional herb medicine widely used in China. In this study, superfine powder ofC. speciosafruit (SCE), ground by supersonic nitrogen airflow at −140°C, was investigated to assess itsin vitroantioxidant activity andin vivoantiphysical fatigue activity. SCE was homogenous(d<10 μm)and rich in antioxidants like polyphenols, saponins, oleanolic acid, ursolic acid, ascorbic acid, and SOD. According to thein vitroexperiments, SCE displayed promising antioxidant activity with powerful FARP, SC-DPPH, and SC-SAR activities. According to thein vivoexperiments, rats supplemented with SCE had prolonged exhaustive swimming time (57%) compared to the nonsupplemented rats. Meanwhile, compared to the nonsupplemented rats, the SCE-supplemented rats had higher levels of blood glucose and liver and muscular glycogen and lower levels of LA and BUN. Lower MDA, higher antioxidant enzymes (SOD, CAT, and GSH-Px) activities, and upregulated Nrf2/ARE mediated antioxidant enzymes (HO-1, Trx, GCLM, and GCLC) expression were also detected in the supplemented group. This study indicates that SCE is a potent antioxidant and antifatigue agent, and SCE could be a promising raw material for the food and pharmaceutical industries.