Thermal contact resistance (TCR) has been recognised as one of the key factor in the high precision thermal design of component structure. In this paper, the TCR between the ammonium dihydrogen phosphate (ADP) crystal and aluminium alloy (5A06) was studied experimentally according to the working characteristics of crystal module in inertial confinement fusion (ICF) device. The effects of interface temperature, contact pressure, surface roughness, heat flow direction, load cycling and crystal cutting method on TCR were obtained by experiments. Results indicated that there is a correlations exists between the TCR and the interface temperature and surface roughness. The TCR decreased with the increase of contact pressure. The effects of contact temperature, surface roughness and contact pressure on TCR were successively reduced according to analysis of variance (ANOVA) with the contributions of 39.5%, 25.6% and 22.7%, respectively. The TCR of heat flow direction from aluminium alloy to ADP crystal was greater than that caused by the reverse heat flow direction. Hysteresis effect was found to occur in the load cycling. This research shows that the TCR has a great influence on the thermal structure design and thermal analysis of the crystal module.