Our previous study has shown that 7 days Chlorella powder pre-supplementation can attenuate the resistance exercise-induced muscle fatigue. The purpose of this study was to determine the effects of Chlorella supplementation for four weeks on exercise-induced muscle damage and maximal muscle strength during recovery. In this randomized, double-blind, placebo-controlled study, 24 college badminton players were recruited, and divided into the placebo or Chlorella trials. The subjects were supplemented with Chlorella powder (4.5 g/ day) or placebo for 28 days, and then challenged to an acute resistance exercises (5 sets of 1 RM, with a 1-min rest between sets) to induce muscle damage. The muscle damage and muscle soreness markers were measured at 24 and 48 hours after exercise challenge in both trials. Maximum muscle strength was determined on day 3, 4, 5 after acute exercise. The results showed that the blood creatine kinase, lactate dehydrogenase activities and muscle soreness were significantly increased, whereas muscle strength was decreased after acute resistance exercise in the placebo trial. However, creatine kinase activities and muscle soreness of participants in the Chlorella trial were significantly lowered compared with placebo trial at 24 and 48 hours following resistance exercise. Furthermore, the maximum muscle strength of leg press on 3rd and 4th day, and leg curl and chest press on 4th and 5th day during recovery period in Chlorella trial were significantly higher than the placebo trial. Our results conclude that Chlorella supplementation can reduce the resistance exercise-induced muscle damage, and decrease muscle fatigue in athletes during the recovery.