The biological activities of Smilax china L. rhizome (SCR), hot water (SCRW) and 70% ethanol extract (SCRE) were analyzed. The total phenolic contents of SCRW and SCRE were 51.7 and 100.5 mg/g, respectively. The measured flavonoid content of SCRW ($67.7{mu}g/g$) was almost double that of SCRE ($31.7{mu}g/g$). SCRE ($IC_{50}=42.4{mu}g/mL$) exhibited stronger antioxidant activity in the DPPH system than the positive control ${alpha}$-tocopherol ($71.3{mu}g/mL$) or butylated hydroxy anisole ($53.8{mu}g/mL$) did. SCRE ($IC_{50}=50.3{mu}g/mL$) also showed stronger ABTS radical scavenging activity, as did ${alpha}$-tocopherol ($67.1{mu}g/mL$). The SOD-like activity and Tyrosinase inhibition activity of SCRW and SCRE showed almost the same pattern. The best SOD-like activity and tyrosinase inhibition activity were measured as 24.9% and 20.3% in SCRW at $1,000{mu}g/mL$, respectively. The cytotoxic effects of the SCR extracts were analyzed via MTT assay on human cancer and normal cells. SCRW and SCRE did not show cytotoxicity up to the concentration of $1,000{mu}g/mL$ against the normal human cell line HEK293. Against human breast cancer cells (MCF-7), SCRW inhibited MCF-7 growth (by 27.6%) better than the anticancer drug cyclophosphamide (15.5%) at $1,000{mu}g/mL$. SCRE ($1,000{mu}g/mL$) inhibited the growth of human lung cancer cells A549 (37.6%) and human stomach cancer cells AGS (53.6%) more effective than did SCRW (21.0% and 35.4%) or CPA (22.2% and 31.7%). These results suggest the potential use of SCRE and SCRW as an excellent antioxidant and antiproliferative substance, respectively.