Objective: Traumatic brain injury (TBI) is a global public health problem. Hyperbaric oxygen (HBO) therapy may be beneficial for TBI because it improves cerebral blood flow into tissues exhibiting low blood flow. This was done to observe the clinical therapeutic effect of different intensities of rehabilitation training and HBO therapy in early stages of TBI. Approach: In this multicenter, randomized, stratified case-controlled prospective clinical trial, we selected 158 patients with moderate-severe TBI and assigned them into (1) a control group receiving routine once-daily ( 1/d) rehabilitation training without HBO, (2) study group A receiving routine 1/d rehabilitation training with HBO, (3) study group B receiving twice-daily (2/d) intensified rehabilitation training with HBO, and (4) study group C receiving 2/d intensified rehabilitation training without HBO, all for 3 months. The cognitive ability, activities of daily life (ADL), and movement ability were assessed before and after training with the Fugl-Meyer Assessment (FMA), Functional Independence Measure (FIM), Modified Barthel Index (MBI), and Mini-Mental State Examination (MMSE). Results: FIM, FMA, MBI, and MMSE scores were improved significantly after 1-, 2-, and 3-month rehabilitation training in all TBI patients ( p < 0.01), and this improvement was especially remarkable in patients who received 2/d intensified rehabilitation training with HBO ( p < 0.01). Innovation: With extensive and intensive research on TBI rehabilitation, it was proved that TBI rehabilitation intervention should be initiated as early as possible. Conclusion: Early intensified rehabilitation training in combination with HBO is more beneficial to the recovery of cognitive, ADL, and movement abilities of TBI patients.