Abstract: Objective: To investigate the association between the cut-point-free physical activity metrics—average acceleration (AvAcc), intensity gradient (IG), and metabolic syndrome (MetS) among rural older adults in China, and to establish the age percentile curves for AvAcc. Methods: A total of 1 525 rural older adults wore wrist-worn accelerometers for seven consecutive days to measure AvAcc and IG. Based on median values of the two metrics, participants were dichotomized and categorized into four subgroups: high AvAcc-high IG group, high AvAcc-low IG group, low AvAcc-high IG group, and low AvAcc-low IG group. MetS was defined according to the Guidelines for the Prevention and Treatment of Type 2 Diabetes in China(2020 edition, part 2). Multivariable logistic regression was used to examine the associations of AvAcc, IG, and their combinations with MetS. Restricted cubic splines (RCS) were applied to explore the dose-response associations between AvAcc and MetS, while generalized additive models were employed to construct percentile curves for AvAcc across age groups. Results: Higher AvAcc was significantly associated with lower odds ratio (OR) value of MetS (P＜0.05), whereas no significant association was observed for IG (P＞0.05). Compared with low AvAcc-low IG group, both of the high AvAcc-high IG and high AvAcc-low IG groups showed significant associations in MetS OR (P＜0.05). RCS analysis demonstrated a linear dose-response association between AvAcc and MetS, with the lowest OR for MetS observed at ≥30 min/day of cumulative walking, including ≥5 min of brisk walking (≈4.6 and 6.5 km/h, respectively). Percentile curves indicated that AvAcc naturally declined with age, accelerating markedly after 70 years. Before the age of 72, participants with AvAcc exceeding 50% of their peers had lower MetS OR values. However, after the age of 72, the MetS OR value was relatively low only when the AvAcc exceeded 75% peers. Conclusions: Among rural older adults, physical activity volume is significantly associated with MetS in a dose-response manner. Regardless of intensity, individuals with higher total volume of activity tend to have a lower OR of MetS. Accumulating at least 30 minutes of walking per day (4.6 km/h), including at least 5 minutes of brisk walking (6.5 km/h), is associated with better metabolic health. After 70, activity levels decline significantly, and among those aged 72 and older, only individuals whose physical activity exceeded 75% peers tend to have more favorable metabolic profiles.