To explore the time effect of cerebral palsy in the rat model of ischemia and hypoxia based on the Zea-Longa score，appearance of the brain tissue，and the expression levels of caspase-9 and caspase-3 in the hippocampus.Methods:Healthy SD rats of 3 weeks old were selected and randomized into normal and model groups.The rat model of cerebral palsy was established by the modified Rice-Vannucci method.On days 1，7，14，and 21 after modeling，the general conditions of the rats in each group was observed and the Zea-Longa score was recorded.On days 7，14，and 21，the modeled rats were sacrificed in batches and the brain tissue was collected.The left brain was observed，and the expression levels of caspase-9 and caspase-3 in the hippocampus were determined.Results:Compared with the normal group，the rats modeled for 1 day presented contraction of the left pupil，abnormal postures，spontaneous or nip-tail left-turning，reduced spontaneous activity，decreased excitability，muscle fibrillation，head fibrillation，twitch，and obvious resistance to capture.The abnormalities gradually weakened over time and almost disappeared 21 days after modeling，with the left pupil being always smaller than the right pupil.The model group had higher Zea-Longa score than the normal group on days 7 and 14(P<0.05).Compared with the normal group，the model group showed different degrees of atrophy and necrosis in the left brain tissue 7，14，and 21 days after modeling.Furthermore，the model group had higher expression levels of caspase-9 and caspase-3 than the normal group on days 7 and 14(P<0.05).Conclusion:The modeling of cerebral palsy was effective for 14 to 21 days in the rat model(3 weeks old) of ischemic and hypoxia，which indicated an intervention periods of 14 days.