Recently, an increasing number of works have argued that the spectral properties of black hole X-ray binaries (BH XRBs) are closely associated with the accretion mode transition. In this work, we investigated whether the evolution of the X-ray light curve was also governed by the accretion modes transition. To test this question, we collected 13 normal outbursts from six BH XRBs with multiple Rossi X-ray Timing Explorer observations during their decay phase. Based on the Γ– correlation, we extracted observations from radiatively efficient accretion flow (REAF, e.g., Shakura–Sunyaev Disk, SSD + corona) and radiatively inefficient accretion flow (RIAF, e.g., advection dominated accretion flow, ADAF). We found that the light curves from REAF and RIAF could be well fitted with the exponential function , respectively. More interestingly, the exponential decay timescale (τe) for REAF is approximately twice that for RIAF (τi), with an average of τe/τi ∼ 2.14. This result supports the theoretical picture of a transition between SSD+corona and ADAF accretion modes. Therefore, our study demonstrates that the evolution of the X-ray light curve-specifically the switch from one exponential decay to another-is regulated by the accretion mode transition between the SSD+corona and ADAF states.

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