Abstract Patent applications have surged in China over the past two decades. Has the application boom been accompanied by a simultaneous drop in the value (quality) of the patents? Our research examines this question by analyzing invention patents in agriculture. Using data from China's State Intellectual Property Office (SIPO) for patents between 1985 and 2005 that had been granted before January 2011, we conduct duration analysis of patent life span and the length of patent renewal with the Weibull and Cox Proportional Hazard modeling respectively. The results show that the value of Chinese agricultural patents, measured by their life span and renewal length, has been improving, although foreign grants are still maintained significantly longer than domestic ones. For domestic grants, private entities, especially companies, are more likely to have a longer patent protection period than public entities. Furthermore, patent value varies significantly across different technological fields, with grants to inventions in complex and emerging technologies such as agricultural biotechnology and agricultural chemicals demonstrating higher value than others. The findings have implications for understanding the impacts of China's innovation policy on global patenting activities as well as China's innovation trajectory in agriculture and other sectors.