Abstract: 【Objective】The study aims to investigate the change in patent quality across different filing periods, applicants and technology fields in China’s agricultural sector when the volume of patent filings rose dramatically. 【Method】Using the total agricultural patents filed in China as a sample, the paper employs statistical and econometric models to examine invention patent  ratios, invention patent grant ratios, grant lapse ratios and patent maintenance period. 【Result】There is no significant difference in grant ratio between domestic applications and foreign applications, but foreign grants are maintained longer than domestic counterparts. At the 0.01 significance level, for domestic applicants, the invention grant ratio of domestic public sector organizations (e.g. research institutes, universities) is a bit higher than that of companies and individuals’ ones; however the probability of renewing patent is significantly smaller than that of companies. The coefficients of time dummies show that both the invention grant ratio and renewal probability of domestic filings are on the rise in recent years. 【Conclusion】It is found that, the quality of Chinese domestic filings has been improved significantly in recent years although it still falls behind that of foreign filings. Particularly the progress in agro-biotechnology is the most striking. Public sectors organizations (universities and public agricultural research institutions) dominate the patenting activities in the agricultural sector and they have a better patent quality than private applicants (companies and individuals), however, most of university patents lapse rapidly in the first three years. The main policy implication is that government should guide and regulate the filing motives of public sector organizations and promote the transfer of agricultural patents from public sector to private sector.

Key words: agriculture, invention patent, applications, patent quality, maintenance period