We present a reflected reprocessing model to study the thermal lag-wavelength relationship in the AGN accretion disk. The main radiation produced from the corona assumed with the lamppost geometry on the axis of the black hole irradiates the accretion disk to affect the temperature structure via reflection processes. Considering the thermal emission of the disk responded to coronal irradiation, we obtain the lag-wavelength relationship of the disk emission by calculating the response function. We then fit the observed data of four Seyfert 1-1.5 galaxies, NGC4151 , Mrk509, NGC5548, and NGC4593, to test the reflected reprocessing model compared with the X-ray spectrum fitting, and the main results present as follows: (I) The actual geometry of the disk corona is more complex than the lamppost. (II) The option of the reference band is sensitive to fitting the observed time lags. (III) The intrinsic bolometric luminosity is larger than the observed luminosity.