With the rapid development of Hall thrusters， iodine fueled Hall thrusters have been paid more and more attention from researchers. In order to deeply understand the internal procedure in the discharge channels of iodine fueled Hall thrusters and provide scientific evidences for optimizing the performances of thrusters and expanding their space applications， a two-dimensional particle-in-cell/direct-simulation-Monte-Carlo/Monte-Carlo-collision (PIC/DSMC/MCC) hybrid model is established with sheath and secondary electron emission. According to the properties of iodine， dissociation and ionization are added. Under the condition of constant channel wall temperature， numerical simulations are carried out for the internal procedure in the discharge channel of a 200 W iodine fueled Hall thruster. The multi-field coupling characteristics of plasma and the interactions between the channel walls and the plasma in the discharge channel are studied. The ion number density， ion axis velocity， and electronic temperature distribution are obtained to study the plasma actions and analyze the parameters of plasma. Compared with xenon， iodine fueled Hall thrusters have a dissociating region with a width of about 2 mm， which is located behind the near-anode region and before the ionization region.