Chitosan is a natural biopolymer that has garnered significant interest in the biomedical field due to its biocompatibility, biodegradability, and non-toxicity. It has been explored for various applications, such as drug delivery, wound healing, tissue engineering, and gene therapy. One of the main advantages of chitosan is its ability to form a gel-like substance in acidic conditions. This property has made it an attractive candidate for wound healing applications, as chitosan-based dressings can help prevent infection and promote tissue regeneration. Additionally, chitosan has been used as a scaffold material for tissue engineering, as it can support cell growth and proliferation. Chitosan has also been investigated as a drug delivery system. Due to its positive charge, it can interact with negatively charged drugs and protect them from degradation in the body. It has been used to deliver a wide range of drugs, including antibiotics, anticancer drugs, and proteins. Another promising application of chitosan is in gene therapy. Chitosan can form complexes with DNA and facilitate gene delivery to cells. This has the potential to revolutionize the treatment of genetic disorders and other diseases. Compared with other kinds of hydrogels based on other materials including polyvinyl acetate, tripolyphosphate, sulfobetaine, chitosan hydrogels have more disadvantages. Chitosan hydrogel is a natural biopolymer-based material that has gained significant attention in recent years due to its unique properties and wide-ranging applications. Chitosan hydrogel has a unique ability to absorb large amounts of water, which makes it an excellent material for wound healing and tissue engineering applications. When the hydrogel comes in contact with a wound, it forms a protective layer that prevents bacterial infections and promotes faster healing. Additionally, chitosan hydrogel has been shown to have anti-inflammatory properties that help reduce pain and swelling. In addition to wound healing and tissue engineering, chitosan hydrogel has also been explored for use in drug delivery systems, where it can be used to encapsulate drugs and release them in a controlled manner. This property makes it an ideal material for developing drug delivery systems for a variety of diseases, including cancer. Overall, chitosan hydrogel is a versatile and promising material with a wide range of potential applications in biomedical and pharmaceutical fields. Its unique properties make it an attractive option for researchers and clinicians looking to develop innovative solutions for various medical problems. However, chitosan hydrogels still have many defects including poor solubility, susceptible to degradation by enzymes, induce an immune response in some individuals, toxicity to the cells, long gelation time with moderate weight percentage hydrogel precursors, etc. For instance, Zeng etc., synthesized a chitosan-PEG hydrogel using UV lamp as initiator. However, the light could be harmful to the cells in the biomedical application. Also, their gelation time is much long than 1 hour if they only use 4% chitosan hydrogel precursors. In this paper, we solved above two defects: long gelation time with moderate weight percentage hydrogel precursors and toxicity from the initiator. We created a hydrogel based on chitosan and 4-arm PEG using maleimide-thiol coupling. We also investigated the hydrogel regarding its gelation speed, swelling behavior, viscoelastic property, and degradation rate.