Objectives To investigate the longitudinal changes in intraocular pressure (IOP) and its associations with refractive error and systemic determinants in a Chinese geriatric population. Design Prospective cohort study. Setting Guangzhou Government Servant Physical Check-up Center, Guangzhou, China. Participants 4413 government employees aged no less than 40 years (41.9% female) attending annual physical and eye examinations were included in this study. The inclusion criterion was having attended the 2010 follow-up examination. The exclusion criteria include glaucoma or intraocular surgery history, IOP 〉21 mm Hg at any visit or without available IOP data at all visits from 2010 to 2014. Primary and secondary outcome measures The outcome measure was IOP at each follow-up visit from 2010 to 2014. Mixed-effect model was used to assess the relationship between longitudinal changes in IOP and potential risk factors. Results For the 2653 participants who had available IOP data at both the 2010 and 2014 follow-up visits, the average change in IOP was an increase of 0.43 (95% CI 0.36 to 0.50) mm Hg. For the whole study population and in the optimised mixed model, there was a non-linear increase of IOP with age (P〈0.001), with greater changes in younger subjects and in women (P〈0.001 and P=0.002, respectively). Elevations in systolic blood pressure, diastolic blood pressure, body mass index (BMI) and fasting plasma glucose (FPG), as well as a myopic shift (all with P〈0.001), during the follow-up were associated with an increasing trend of IOP, while serum lipids were found to be not significantly associated. Conclusions In this cohort of elderly Chinese adults, IOP increases non-linearly with ageing. People with increasing blood pressure, BMI, FPG and myopic progression are more likely to have IOP elevation over time.