Diarrhea after vaccination may be a reaction to vaccination or a gastrointestinal disease. It is recommended to confirm the diagnosis and receive treatment according to the symptoms under the guidance of a doctor. 1. Vaccination reaction: Diarrhea after vaccination with the new crown vaccine is mostly transient diarrhea, which is a normal post-vaccination reaction. If the diarrhea is infrequent and not serious, it can be left untreated and will usually resolve on its own within two or three days. 2. Gastrointestinal diseases: If the number of diarrhea after vaccination is high, and accompanied by nausea, vomiting and other symptoms, we can not rule out the existence of gastrointestinal diseases, such as chronic gastritis, enteritis and other causes. Diarrhea after vaccination may be a reaction to vaccination or gastrointestinal disease, it is recommended to confirm the diagnosis and targeted treatment under the guidance of a doctor.