Therefore, we carried out the thesis "investigating antioxidant activity and total phenolic content of extract from Polygonum cuspidatum Polygonaceae" with the targets: - Survey of antioxidant effects of total extract and fractional - Building a process for quantifying the total phenolic content of total extract with antioxidant effect Result: The 70% ethanol extraction‟s antioxidant is similar to 16, 82% of ascorbic acid.