Tropical Pacific decadal variability (TPDV) refers to the decadal fluctuations in sea surface temperature anomalies (SSTA) over the tropical Pacific and plays a critical role in modulating regional and global weather and climate. Nevertheless, the long-term change in TPDV frequency and its underlying physical drivers remain insufficiently understood. In this study, we systematically investigate the frequency change of TPDV and the associated dynamical mechanisms. Observational evidence reveals a pronounced long-term blue shift in TPDV, characterized by a tendency toward higher-frequency signals in recent decades. The periods of decadal SSTA in the subduction regions of both the northern and southern subtropical Pacific exhibited a long-term shortening, which contributes to the blue shift of TPDV. Furthermore, the decadal heat transport anomalies associated with the subtropical cell (STC) exhibited faster phase transitions across the tropical Pacific. This phenomenon indicates that the STC facilitates a more rapid propagation of decadal thermal anomalies, thereby substantially influencing the frequency modulation of TPDV.