In a wide range of events, people may be acutely exposured to chemical substances. Particular hospital preparedness plans and vital resources are essential for appropriate health-care measures. The present study aimed to conduct a systematic review to summarize and evaluate the existing evidence on hospital preparedness plans or protocols against chemical incidents and threats. In this aim, through May 15, 2018, 5 electronic databases were searched in MEDLINE (PubMed, Scopus, Web of Science, Cochrane Library, and Google Scholar) for the following key words: hospital preparedness, plan, protocol, chemical incident, and chemical threat. The final review included 11 peer-reviewed papers that met inclusion criteria. The systematic review was performed using the Preferred Reporting Items for the Systematic reviews and Meta-Analysis protocol (PRISMA) (www.prisma-statement.org). Finally, of 16,540 selected papers, 11 papers were included in the final analysis. The thematic analyses revealed 11 major categories of chemical incidents and threats planning, such as planning requirements, planning prerequisites, preparation team member (multidisciplinary team), decontamination, personal protective equipment, education and training, job descriptions and roles, communication, database, staff /volunteer organization, as well as planning barriers and challenges for chemical incidents. Most countries have launched hospital preparedness planning against chemical incidents and threat activities, but the preparedness of hospitals is often less than desirable. Many items, such as databases, hospital preparation team members, communications, etc., are still challenging.