Polyethylene glycol is a water-soluble polymer that has been widely approved by the FDA for use as an additive in drugs and food. Modification with polyethylene glycol can increase the water solubility of protein drugs, reduce their immunogenicity, and improve their stability in vitro and in vivo, such as prolonging their half-life. Polyethylene glycol can also be used to modify other drugs to increase their water solubility and improve their absorption rate, especially for small molecule drugs with poor water solubility. Modified with polyethylene glycol can greatly reduce the toxic side effects of the drug, improve its circulation time in the body, and enhance its efficacy. DiQi has the technology to prepare polyethylene glycol derivatives with different end functional groups and molecular weights to meet the needs of modifying different drugs with different reactive functional groups, which can make drugs targeted.