Over the past two decades, Olympic swimming performance has improved. However, less attention has been given to the evolution of Olympic Qualification Time (OQT) standards. This retrospective observational study analyzed event-specific qualification standards for all male pool swimming events. Data were extracted from publicly available documents and competition reports. Descriptive statistics, percentage change calculations, Pearson correlation analysis, and paired-sample t-tests between Olympic cycles from 2008 to 2028 were performed. For 2028, the OQTs were defined as the 14th fastest entry time from the 2024 Olympic Games. Across all events, the mean cumulative reduction in OQTs between Beijing 2008 and Los Angeles 2028 was 2.86 ± 0.54%, corresponding to an average proportional decrease of 0.6% per Olympic cycle, with trend analysis confirming statistical significance (p < 0.001). Event-level analysis revealed the greatest tightening in the 100 m breaststroke (−3.74%) and 100 m butterfly (−3.25%). When grouped by distance, sprint events (50–100 m) showed the strongest overall tightening (−3.57%), followed by middle-distance (200–400 m, −2.08%) and long-distance (800–1500 m, −2.45%). When grouped by stroke, butterfly (−3.28%) and freestyle (−3.20%) showed the largest decrease, whereas individual medley (−2.29%) demonstrated the smallest decrease. A strong positive correlation was observed between OQT tightening and Olympic performance improvement across events (r = 0.74). These findings indicate that OQTs have become demanding and broadly aligned with elite performance progression, providing applied benchmarks for coaches and performance staff.