To study the main active components and antioxidant activity in vitro of extracts from Callisia repens, the contents of main active components such as total flavonoids, total anthocyanin and total sugar in the extracts were studied by spectrophotometry. The components and content of 18 kinds of metals were determined by ICP-MS mass spectrometry. Finally, the oxidative activity of the extract was evaluated by spectrophotometry. Results showed that the content of flavonoids, the total protein, the total sugar and the total anthocyanin in C. repens extract powder were 2.04%, 1.83%, 55.2% and 7.2%, respectively. Beneficial trace elements such as Ca, Mn, Mg in C. repens extracts were higher, while harmful heavy metals such as Pb, Hg, Ag, Co, Ge were very tiny or not detected at all. The IC50 of C. repens was 0.265 mg/mL for scavenging DPPH·, and 1.16 mg/mL for scavenging ·OH free radical, the total reducing power of 1 mg extract was equivalent to that of 39 μg of Vc, and the extract showed no regular chelating power to ferrous ions. In conclusion, C. repens extracts have high content of natural active components, but extremely low content of the harmful heavy metals, and C. repens extract has good antioxidant capacity. Its antioxidant activity is realized by a variety of active factors through a synergistic mechanism. Thus, C. repens extract has great potential for developing into functional foods.