In this study, we investigated the variation in free sugars, organic acids, antioxidant activity and anti-inflammatory effect of Solanum nigrum Linne fruits according to harvest time. Four kinds of free sugars (fructose, glucose, sucrose, maltose) were detected in S. nigrum fruit, and the free sugar contents varied significantly with harvest time. Organic acid content of S. nigrum fruit showed the highest in malic acid and acetic acid, and the highest content of total organic acids was found in S. nigrum fruit harvested on October 18th and October 25th. For the total polyphenol content, S. nigrum fruit harvested on October 18th was the highest. The strongest DPPH and ABTS radical scavenging activity was showed in S. nigrum fruit harvested on October 11th and October 18th. The anti-inflammatory activity and antioxidant effects were the highest in the ethanol extract from S. nigrum fruit collected on October 18th and October 11th. Thus, it seems the best to harvest of S. nigrum fruit harvested on October 11th and October 18th.