This paper presents high-resolution N-body simulations of cold dark matter (CDM) halos, aiming to understand their internal structure and dynamics. The simulations show that as mass and force resolution increase, the inner density profiles of halos become steeper, approaching a slope of -4/3 in the central regions. At the highest resolution, the simulations resolve over 1000 dark halos within a single cluster potential, allowing for the first time a comparison of dark matter distribution with galaxy observations in clusters. The simulations start with a candidate cluster identified from a large cosmological volume. The region is then resimulated at higher resolution, with the power spectrum matched at boundaries. The new initial conditions are integrated using the PKDGRAV code, with high mass and force resolution. The simulations show that the inner slope of density profiles can reach -1.4, likely due to resolving more halos collapsing at early epochs when the universe was denser. The results show that halos within clusters have density profiles that are well fit by NFW profiles, with concentrations higher than those in isolated environments. Halos that lose mass through tidal stripping have steeper outer density profiles. The distribution of halo orbits is close to isotropic, with most halos passing within 0.1 R200 of the cluster center. The simulations also show that overmerging leads to a substructure distribution that is anti-biased with respect to the global mass distribution. Mergers between halos with mass ratios larger than 10:1 occur frequently in the cluster vicinity, but are rare within the virial radius. The mass bound to resolved dark matter halos is about 10% of the cluster mass, varying with radius. These results provide new insights into the dynamics and structure of dark matter halos within clusters.This paper presents high-resolution N-body simulations of cold dark matter (CDM) halos, aiming to understand their internal structure and dynamics. The simulations show that as mass and force resolution increase, the inner density profiles of halos become steeper, approaching a slope of -4/3 in the central regions. At the highest resolution, the simulations resolve over 1000 dark halos within a single cluster potential, allowing for the first time a comparison of dark matter distribution with galaxy observations in clusters. The simulations start with a candidate cluster identified from a large cosmological volume. The region is then resimulated at higher resolution, with the power spectrum matched at boundaries. The new initial conditions are integrated using the PKDGRAV code, with high mass and force resolution. The simulations show that the inner slope of density profiles can reach -1.4, likely due to resolving more halos collapsing at early epochs when the universe was denser. The results show that halos within clusters have density profiles that are well fit by NFW profiles, with concentrations higher than those in isolated environments. Halos that lose mass through tidal stripping have steeper outer density profiles. The distribution of halo orbits is close to isotropic, with most halos passing within 0.1 R200 of the cluster center. The simulations also show that overmerging leads to a substructure distribution that is anti-biased with respect to the global mass distribution. Mergers between halos with mass ratios larger than 10:1 occur frequently in the cluster vicinity, but are rare within the virial radius. The mass bound to resolved dark matter halos is about 10% of the cluster mass, varying with radius. These results provide new insights into the dynamics and structure of dark matter halos within clusters.