To investigate the effect of intracranial pressure fluctuation in severe brain trauma. Methods 357 patients with severe craniocerebral trauma admitted to our hospital from March 2019 to May 2023 were selected as the study subjects, Patients were divided into good prognostic group (n=208) and (n=149), Comparing the clinical data between the two patient groups, Differences in intracranial pressure fluctuation characteristics before and after 1,2,3,4,5, and 6d, Preoperative and last follow-up neurological function score; Using the minimum absolute shrinkage selection operator (LASSO) regression method and multivariate Logistic regression analysis to adjust for confounding variables, To explore the independent influencing factors affecting the poor prognosis of patients; Build a structural equation prediction model and validation. Results In the two groups, total protein, C reactive protein and amplitude were statistically significant (P <0.05); respectively, ICP at 1-6d (P <0.05), GCS score and GOS score in the last follow-up were higher than P <0.05), and NHISS score in the good prognosis were significantly lower than the preoperative group (P <0.05). After adjustment for potential confounders by LASSO analysis and multivariate Logistic regression analysis, total protein, C reactive protein, amplitude, intracranial pressure, GCS score, NHISS score, and GOS score were all independent factors affecting the poor prognosis of metastasis flap incision after bone flap decompression in patients with severe craniocerebral trauma. No non-linear dose-response relationship existed regarding the strength of the association of ICP level with severe traumatic brain injury outcome in either men or women (P <0.05). Structural equation modeling showed that total protein, C-reactive protein, amplitude, intracranial pressure, GCS score, NHISS score, and GOS score were direct and indirect factors of poor patient prognosis, and the total path coefficient was statistically significant (P <0.05). The prediction model showed good discrimination and independence in this study. Conclusion The intracranial pressure level varies significantly in patients with severe craniocerebral injury after decompression with metastasis flap incision, and when the C reactive protein, intracranial pressure level and NHISS score increase, the total protein, amplitude, GCS score and GOS score decrease can affect the poor prognosis of patients with severe craniocerebral trauma.