Hainan. Yangshengtang is Yangshengtang Pharmaceutical Co., Ltd., established in 1993. Headquartered in Hainan, the company is mainly engaged in the production of health care products and medical nutrition. Products cover a wide range of people. Among its health products, natural vitamins are famous. A listed company is a joint stock limited company, which must meet certain conditions besides being approved to be listed and traded on the stock exchange.