  H1743-322 is one of the few black hole candidates (BHCs) in low-mass X-ray
binaries that shows mHz quasi-periodic oscillations (QPOs) that are not
associated with the more common type A, B and C oscillations seen in the X-ray
light curves of typical BHCs systems. To better understand the physical origin
of the mHz oscillations, we carried out a phase-resolved spectroscopic study of
two RXTE observations of this source. As previously reported, the averaged
energy spectra of H1743-322 shows a strong iron line at $\sim6.5$ keV. Here we
found evidence that the line flux appears to be modulated at twice the
frequency of the mHz QPO. This line flux modulation is very similar to the one
previously found for the type-C QPO in this source. We interpret the possibly
periodic line flux modulation with this mHz QPO in terms of Lense-Thirring
precession of the inner flow, and discuss the possible connection with the
modulation of the line properties with the type-C QPO frequency.
