Background <p>Data regarding the cardiometabolic index (CMI) changes and stroke are limited. Thus, our objective was to investigate the correlation between CMI changes and stroke among middle-aged and elderly individuals in China.</p> Methods <p>The China Health and Retirement Longitudinal Study (CHARLS) used a multistage stratified sampling approach to survey individuals aged 45 and above. Changes in CMI were calculated as the differences in CMI between 2015 and 2012 divided by the number of years. The lowest third of the CMI changes were negative and categorized as the ‘loss’ group; the middle third exhibited a steady increase and was classified as the ‘stable’ group; the top third showed positive changes and was categorized as the ‘gain’ group. Subsequently, we monitored the participants from 2015 to 2020.</p> Results <p>Out of the 4,365 participants observed during the five-year follow-up period, 356 individuals (8.2%) developed stroke. Compared with the lowering group, the ratio (<i>OR</i>) for stroke in the stable group was 1.503 (95% <i>CI</i>: 1.096–2.061); the <i>OR</i> for stroke in the gain group was 1.528 (95% <i>CI</i>: 1.117–2.089). A nonlinear relationship was observed between CMI changes and stroke (<i>P</i>_association&lt;0.001, <i>P</i>_nonlinearity&lt;0.05).</p> Conclusion <p>Our findings indicate a nonlinear and positive association between CMI changes and stroke in Chinese middle-aged and older people, which can help to develop interventions to prevent stroke with strategies for high-risk groups.</p>