Osteoporosis is an age-related disease, but the impact of the season on osteoporosis should not be underestimated. A study conducted in Norway showed that the incidence of fractures in older adults was significantly higher in winter than in summer, and significantly higher in cold climates than in warm climates. Vitamin D is an important hormone for calcium absorption, but there is very little natural vitamin D in food, and only slightly more in deep-sea fish liver. Vitamin D in the human body is basically synthesized through ultraviolet light exposure to the skin. In winter, the vitamin content in the body is significantly lower than in summer because the sun is slanted and ultraviolet light is reduced, while people wear more clothes and have less skin exposure. A survey done in Australia and New Zealand showed that 25(OH) vitamin D levels in adult blood are 10-20 nmol/L lower in winter than in summer, so calcium absorption is reduced in winter. In addition, blood levels of vitamin D hormone are critical to reducing falls and increasing muscle strength and coordination. When vitamin D levels drop in winter, older adults are more prone to falls and osteoporotic fractures. A study conducted in Sweden showed that the risk of fractures in people with low blood levels of the vitamin increased by more than half compared to people with normal vitamin D levels. In addition, due to the cold weather, people’s activities are also relatively reduced, which also affects the absorption of calcium in the body. Insufficient calcium intake increases natural bone resorption, which also aggravates osteoporosis. People’s clothing increases in winter, the flexibility of activities will be greatly reduced. Reduce exercise for a week, the body’s coordination will become worse, the chance of falling increases, plus the elderly are prone to osteoporosis, the brittleness of the bone increases, and fractures are likely to occur after a fall. In winter, the road will become slippery because of snow or ice, so the elderly will easily fall when they go out, especially at night when the lighting is not good. One winter, there was icy weather in Tianjin, and the ground was as smooth as a mirror, so the number of people who fell suddenly increased, and in just one day, there were more than 200 patients who went to Tianjin Hospital to confirm the fracture. Therefore, people, especially the elderly, should be extra careful in winter. One is to take adequate amount of vitamin D, preferably with active vitamin D. The amount of supplementation should be appropriately increased in winter than in summer to reduce the risk of osteoporosis and osteoporotic fractures. In addition, the elderly should be more careful in winter. If the weather is good, the elderly should go out properly to receive sunlight and move appropriately to maintain muscle strength and coordination, if they encounter rain or snow, they should avoid going out, and if they do, they must walk carefully to avoid the occurrence of falls. Of course, the treatment of osteoporosis is not effective in a short time, so it should be started as early as possible and not to wait for winter to think about it.