Polyurethane thickener, referred to as HEUR, is a hydrophobic group-modified ethoxy polyurethane water-soluble polymer, which belongs to nonionic associative thickener. HEUR is composed of a hydrophobic group, a hydrophilic chain and a polyurethane group. Hydrophobic groups play an associative role and are the determinants of thickening. They are usually oleyl, octadecyl, dodecylphenyl, and nonylphenol. The hydrophilic chain can provide chemical stability and viscosity stability. Polyethers such as polyoxyethylene and its derivatives are commonly used. The HEUR molecular chain is extended by polyurethane groups. The polyurethane groups used are IPDI, TDI, HMDI, etc. The structural feature of associative thickeners is the capping of hydrophobic groups. However, some commercially available HEURs have a degree of substitution of less than 0.9 at both ends, and the best is only 1.7. The reaction conditions should be strictly controlled to obtain a polyurethane thickener with a narrow molecular weight distribution and stable performance. Most HEURs are synthesized by a stepwise polymerization process, so commercially available HEURs are generally mixtures of broad molecular weights.