Abstract: To clarify the theoretical positioning of "block training" and the critical role of "mesocycles" in classical training periodization theory, this study employs a comprehensive methodology with literature review, logical deduction and case analysis to systematically investigate the theoretical connections between block training and mesocycles, elucidate the characteristics and functions of mesocycles within the Chinese sports training periodization framework, and reveal the mechanisms through which different mesocycle organizational patterns influence competitive readiness. Key findings include: ① The absence of mesocycles disrupts the systemic integrity of macrocycle training phases, undermining the inherent logic of competitive state development. Block training essentially represents the optimized reconstruction of mesocycle structures from classical periodization theory. Through precise theoretical positioning, its advantages can be effectively integrated into traditional periodization theory frameworks. ② Mesocycles theory holds the pivotal significance in China's distinctive sports training periodization system, which enables coaches to appropriately regulate the cumulative effects of microcycle training series, ensuring a high-adaptive development of training stimuli while preventing the potential adaptation impairment from excessive training load accumulation. This mechanism safeguards the successful cultivation of macrocycle competitive states. ③ Reemphasizing mesocycle functions can purposefully maintain elevated "training stimulus states" to meet the demands of commercial multi-event competitions. More importantly, it fully activates the nested synergy mechanism of macrocycles, mesocycles and microcycles in classical training periodization theory. This approach aligns with the requirements of China's Olympic Glory Program, systematically developing athletes' competitive readiness for major international competitions and national honor pursuits.