Background. The clinical efficacy of the third Military Medical University formula (TMMU formula) for fluid resuscitation stage was evaluated to improve the treatment level of adult patients with extensive burns during the shock stage. Methods. Retrospective analysis of the data of 55 patients undergoing fluid resuscitation according to the TMMU formula within six hours after burn injury. The following indicators were collected: (1) demographic and injury information; (2) fluid resuscitation information; (3) efficiency information, including cardiovascular function, liver function, renal function, coagulation function evaluation indicators, blood concentration, and average urine output index. Results. (1) In the first and second 24 hours after injury, the median fluid rehydration coefficient was 1.68 ml/kg·(%) TBSA and 1.15 ml/kg·(%) TBSA, the median ratio of crystal to colloid was 2.24 and 1.67, and the median urine output index was 0.75 ml/kg·h and 1.05 ml/kg·h, respectively. (2) The actual fluid volume during patient resuscitation is higher than the formula calculated volume, and this difference is more obvious in patients with burn area ≥80%. (3) In the second 24 hours, the value of the actual total fluid volume minus the formula total volume in the group with crystal to colloid ratio ≤2 was significantly lower than that in the ratio >2 group. (4) At 24 and 48 hours after injury, the cardiovascular function, liver function, renal function, and coagulation function were better than those before fluid resuscitation. Conclusions. Early application of the TMMU formula for fluid resuscitation in adult patients with extensive burns is safe and effective, but the actual input volume often exceeds the volume calculated by the formula, especially in the second 24 hours after burn injury and in patients with larger burn areas. Increasing the colloid input volume can help reduce the total amount of fluid used for resuscitation.