Objective To observe the therapeutic effects of hyperbaric oxygen (HBO) at different time points in infants with cerebral palsy.Methods Sixty cases of cerebral palsy with an age of 3 months were randomly divided into 4 groups:group 1,2,3,4,each consisting of 15 cases.All the infants of the 4 groups were given routine rehabilitation treatment until they were 1 year old.The sick infants in group 1,2 and 3started HBO therapy at the following ages:3 to 4 months old,4 to 6 months old and over 6 months old respectively,with a treatment course of 8 weeks and a total of 40 sessions.The infants in groups 4 were not treated with HBO.Gross motor function was evaluated with Gross Motor Function Measure (GMFM).Intelligence was evaluated with Gesell Development Scale.Then,developmental quotient and total developmental quotient in gross motor,fine motor,adaptation,language and individual-social domains were calculated.Results At one year old,GMFM,developmental quotients in the above five domains and total developmental quotients of all the sick infants in the 4 groups improved significantly,when compared with those before treatment.Of all the patients in the 4 groups,the patients in groups 1 improved more significantly than those in group 2,3 and 4,with statistical significance (P ＜ 0.05).The patients in groups B improved more significantly than those in group 3 and 4,also with statistical significance (P ＜ 0.05).No statistical significance could be noted in therapeutic effects,when a comparison was made between group 3 and 4 (P ＞0.05).No serious adverse reactions could be noticed in the patients of the 4 groups during treatment.Conclusions Therapeutic time points of HBO therapy played an important role in the treatment of cerebral palsy in infants.The earlier the HBO therapy was implemented,the better the treatment.Optimal therapeutic effects could be achieved,if HBO therapy was started within 3 to 4 months after onset of the disease.Less optimal therapeutic results could be achieved,if HBO intervention was given within 4 to 6 months.And there would be no significant effects,if HBO therapy was started 6 months after the onset of disease.