Highland barley tea (HBT) is made from roasted barley seeds and is abundant in β-glucan, amino acids, minerals, phenolics, and other natural active ingredients. These natural compounds found in whole grains have been shown to slow aging and positively affect skeletal muscle function. As a result, studying the effects of HBT on the skeletal muscle health of the elderly population is critical from a scientific and societal standpoint for improving their health status and reducing the medical burden on society. The antioxidant activity and the content of natural active substances were used as indicators to screen the optimal process of HBT brewing. The effects of long-term HBT consumption on aging in mice were investigated by using HBT as a substitute for drinking water in naturally aging mice for a 5-month intervention. Afterward, various factors were measured, such as basic physiological indices, inflammation, plasma metabolites, skeletal muscle function, and exercise capacity, to evaluate the effects of HBT on aging in mice. Long-term consumption of HBT reduced body and spleen weight, increased body weight percentage of skeletal muscle, and reduced plasma inflammation levels in aging mice. Metabolomic results showed increased plasma levels of the mitochondrial marker short-chain acylcarnitine and some amino acids. Additionally, there was a decrease in bile and long-chain acylcarnitine. The level of fibrosis in the gastrocnemius muscle of aging mice was suppressed, and the percentage of type I muscle fibers was increased, improving the endurance of the mice. Thus, long-term consumption of HBT may reduce body weight and increase skeletal muscle mitochondrial activity and exercise capacity in aging mice by reducing inflammation levels and alleviating mitochondrial damage.