Objective We investigated the effects of ICAM5 in the hippocampus on the alcohol drinking preference of mice, and the potential mechanisms. Methods An alcohol two-bottle choice model was developed in 8-week-old male C57BL/ 6J mice, which were randomly divided to two groups: water group and alcohol group. The protein expression of ICAM5 in the hippocampus, amygdala, and medial prefrontal cortex was detected. An ICAM5-overexpressing adeno-associated virus was constructed and injected into the hippocampus by stereotaxic method. The expression level of ICAM5 protein in the hippocampus was detected by immunofluorescence and Western blot. We then detected the alcohol preference and locomotor activity of mice with a conditioned place preference (CPP) experiment, open field test, and lossof-righting reflex test. Western blot analysis was used to identify the neuron F-actin / G-actin ratio. Using Golgi staining, the morphology of dendritic spines was identified. Results The expression of ICAM5 in the hippocampus of alcohol two-bottle choice model mice in the alcohol group was considerably lower than that of the water group ( P<0. 001). The specific expression of ICAM5 in the hippocampus of mice was observed by fluorescence microscopy. In the open field experiment,the staying time and moving distance of the AAV-ICAM5 group were significantly increased compared with those of the control group ( P<0. 01). In the CPP experiment, the residence time of AAV-ICAM5 mice in the alcohol-paired compartment was significantly lower than that of control mice ( P<0. 001). In the loss-of-righting reflex experiment,overexpression of ICAM5 significantly reduced sedation latency ( P<0. 01), but significantly shortened the duration of sedation (P<0. 001). Compared with AAV-mCherry +Water group, the ratio of F-actin / G-actin in the hippocampus was significantly increased after drinking ( P<0. 01 ), but after ICAM5 overexpression, their F-actin / G-actin ratio was significantly decreased (P<0. 001). Compared with AAV-mCherry + Water group, the density of dendritic spines in the hippocampal CA1 region was increased (P<0. 001), but the density of dendritic spines in the AAV-ICAM5+Alcohol group was significantly decreased (P<0. 01). Conclusions ICAM5 modulated the expression of cytoskeleton proteins to change the structural plasticity of dendritic spines, which contributed to alcohol-drinking and locomotor behavioral changes in mice.