Background　Cholesterol　is　a　critical　component　of　the　human　body,　particularly　within　the　brain,　where　it　plays　an　essential　role　in　maintaining　cellular　structure　and　function.　In　addition,　the　blood　lipid　profile　has　been　recognized　as　a　significant　factor　influencing　cognitive　performance.　However,　the　association　between　the　ratio　of　total　cholesterol　(TC)　to　high-density　lipoprotein　cholesterol　(HDL-C)　and　cognitive　function　remains　unclear.　Methods　This　community-based,　cross-sectional　study　was　conducted　using　data　from　middle-aged　and　older　adults　(aged　＞=　45　years)　participating　in　the　China　Health　and　Retirement　Longitudinal　Study　(CHARLS).　The　primary　exposure　of　interest　was　the　ratio　of　TC　to　HDL-C,　while　the　main　outcome　was　cognitive　function,　assessed　using　cognition　scores.　The　association　between　the　TC-HDL-C　ratio　and　cognitive　performance　was　examined　using　multiple　linear　regression　analyses　and　restricted　cubic　spline　modeling　to　assess　potential　nonlinear　relationships.　Results　A　total　of　8,914　participants　were　included　in　the　analysis.　Within　a　certain　range,　a　higher　TC-HDL-C　ratio　was　significantly　associated　with　improved　cognitive　scores　(p　＜　0.05)　among　middle-aged　and　older　adults.　This　relationship　remained　significant　even　after　adjusting　for　sociodemographic　and　health-related　factors.　Moreover,　restricted　cubic　spline　analyses　revealed　a　significant　nonlinear　association　(p　for　nonlinearity　＜0.05)　between　the　TC-HDL-C　ratio　and　cognition　scores.　Subgroup　analyses　further　highlighted　differential　effects　of　the　TC-HDL-C　ratio　across　specific　population　subgroups.　Sensitivity　analyses　consistently　supported　the　robustness　of　the　observed　relationship　between　the　TC-HDL-C　ratio　and　cognitive　function.　Conclusion　Our　findings　confirm　a　significant　nonlinear　relationship　between　the　TC-HDL-C　ratio　and　cognitive　performance　in　middle-aged　and　elderly　individuals,　even　after　adjusting　for　sociodemographic　factors.　These　results　underscore　the　potential　importance　of　maintaining　an　appropriate　TC-HDL-C　ratio　to　support　cognitive　health　in　aging　populations.