Yes, a 40-year-old woman can wear a beautiful back. Age is not a limiting factor in wearing a beautiful back. Women of any age can wear beautiful backs as long as they feel comfortable. However, it should be noted that wearing beautiful back for a long time may have a certain impact on the chest and back, such as pressing the chest to make the chest shape not full enough and restricting the back. Therefore, please pay attention to the time and frequency when wearing the beautiful back, and wear it in moderation to avoid discomfort.