【Abstract】 Objective We investigated the effects of ICAM5 in hippocampus of mice alcohol drinking preference, and potential mechanisms. Methods A alcohol two-bottle choice model was developed by 8-week-old male C57BL/6J mice, randomly divided to two groups, the control group and alcohol group. The protein expression of ICAM5 in the hippocampus, amygdala, and medial prefrontal cortex was detected. ICAM5 overexpressed adeno-associated virus was constructed and injected into the hippocampus by stereotaxic method. The expression level of ICAM5 protein in hippocampus was detected by immunofluorescence and Western blot. Then detected the alcohol preference and locomotor activity of mice with the open field test, conditioned place preference experiment, and loss of righting reflex test. Western blot analysis was used to identify neuron F-actin/G-actin ratio. Using Golgi staining, the morphology of dendritic spines was identified. Results In the alcohol two-bottle choice model, the expression of ICAM5 in the hippocampus of mice in the alcohol group was considerably lower than the control group. 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 AAV-ICAM5 group were significantly increased compared with 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 lose the righting reflex experiment, overexpression of ICAM5 significantly reduced the sedation latency (P < 0.01), but significantly shortened the duration of sedation (P < 0.001). Compared with the control group, the ratio of F-actin/G-actin in hippocampus was significantly increased after drinking (P < 0.01). But after ICAM5 overexpression, the F-actin/G-actin ratio was significantly decreased (P < 0.001). Compared with the control group, the density of dendritic spines in hippocampal CA1 region was increased after drinking alcohol (P < 0.001), but the density of dendritic spines in AAV-ICAM5+EtOH group was significantly decreased (P < 0.01). Conclusions ICAM5 may modulated the expression of cytoskeleton protein to change structural plasticity of dendritic spines, which contribute to alcohol drinking and locomotor behaviors change of mice.