  We explore the coupling between the accretion flow and the jet in black hole
X-ray binary (BHXRB) MAXI J1348-630 by analyzing the X-ray and radio
observations during its 2019 outburst. We measure the time delay between the
radio and Comptonization fluxes with the interpolated cross-correlation
function. For the first time, we find that the radio emission lags behind the
X-ray Comptonization emission by about 3 days during the rising phase covering
the rising hard state and the following soft state. Such a long radio delay
indicates that the Comptonization emission most likely originates from the
advection-dominated accretion flow rather than the jet in this source. The
Comptonization luminosity $L_{\rm C}$ in 0.1-100 keV and the radio luminosity
$L_{\rm R}$ at 5.5 GHz, after considering the radio delay of $\sim 3$ days,
follow the correlation with a slope $\beta = 3.04 \pm 0.93$, which is much
steeper than the previously reported $\beta = 0.6$ or 1.40 using the total
luminosity in the limited band (e.g., 1-10 keV) in the literature. This
highlights the necessity of considering (1) the time delay, (2) the spectral
decomposition, and (3) the broad energy band, in the radio-X-ray correlation
analysis. As the jet reappears during the decaying phase (covering the soft
state and the following decaying hard state) and the mini-outburst, the
Componization and the radio emission appear to be almost simultaneous. And, the
radio-Compton correlation during the mini-outburst becomes shallow with the
correlation slope $\beta = 1.11 \pm 0.15$. These indicate an intrinsic
difference in the accretion-jet coupling physics between the main outburst and
the mini-outburst.
