This study explores the effects of heat treatment on the nutritional components and antioxidant activity of peanuts, aiming to optimize the utilization of phenolics and key nutrients in peanuts. The peanuts available in the market are categorized into those with red skins and those without. They underwent three different heat treatments: boiling, frying, and baking. The effects of these treatments on the nutritional components (protein, fat, carbohydrates, and moisture), total phenolic content (TPC), and DPPH free radical scavenging ability of the peanuts were measured and compared with those of untreated peanuts. The results indicated that three heat treatments differentially affected the nutritional components of peanuts, particularly causing significant losses in protein, carbohydrates, and minerals. Boiling had an inhibitory effect on the TPC and antioxidant activity of peanuts, causing reductions of TPC by 39.85% and 25.25% for peanuts with and without skins, respectively. Conversely, frying and baking had a promoting effect on the TPC and antioxidant activity (increasing TPC by 8.30%, 19.43% and 6.08%, 44.14% for peanuts with and without skins, respectively). This research provides valuable insights into the processing conditions and consumption methods of peanuts.