  Magnetic clouds (MCs) are the interplanetary counterpart of coronal magnetic
flux ropes. They can provide valuable information to reveal the flux rope
characteristics at their eruption stage in the corona, which are unable to be
explored in situ at present. In this paper, we make a comprehensive survey of
the average iron charge state (<Q>Fe) distributions inside 96 MCs for solar
cycle 23 using ACE (Advanced Composition Explorer) data. As the <Q>Fe in the
solar wind are typically around 9+ to 11+, the Fe charge state is defined as
high when the <Q>Fe is larger than 12+, which implies the existence of a
considerable amount of Fe ions with high charge states (e.g., \geq 16+). The
statistical results show that the <Q>Fe distributions of 92 (~ 96%) MCs can be
classified into four groups with different characteristics. In group A (11
MCs), the <Q>Fe shows a bimodal distribution with both peaks higher than 12+.
Group B (4 MCs) presents a unimodal distribution of <Q>Fe with its peak higher
than 12+. In groups C (29 MCs) and D (48 MCs), the <Q>Fe remains higher and
lower than 12+ throughout ACE passage through the MC, respectively. Possible
explanations to these distributions are discussed.
