The invention discloses a weak-acid medicated bath lotion capable of moistening skin and dispelling dandruff for old people. The medicated bath lotion is prepared by the following Chinese medicinal materials in parts by weight: 40 to 60 parts of ginseng, 70 to 80 parts of epimedium herb, 30 to 50 parts of Asparagi Radix, 30 to 50 parts of Ophiopogon japonicus, 30 to 50 parts of polyghace seche, 40to 60 parts of herba siegesbeckiae, 70 to 80 parts of Dictamnus dasycarpus Turcz, 30 to 50 parts of Chinese angelica, 30 to 50 parts of Radix Saposhnikoviae, 40 to 60 parts of mulberry leaves, 40 to60 parts of yerbadetajo herb, 70 to 80 parts of Sophora flavescens, 40 to 60 parts of broom cypress fruit, 30 to 50 parts of tree peony bark, 70 to 80 parts of Smilax glabra, 40 to 60 parts of Sophorajaponica branches, 1 to 2 parts of mint, and 70 to 80 parts of radix scrophulariae. The pH value of the weak-acid medicated bath lotion is weakly acidic, and the medicated bath lotion has the health-care effects of moistening dryness, dispelling dandruff, relieving itching and relieving itching, repairing skin barrier and cleaning skin, is suitable for the rehabilitation of skin dryness, desquamation and itching in middle-aged and elderly people, and is also suitable for daily skin cleansing and nursing for middle-aged and elderly people.