Objective To construct a multivariate regression equation for cerebrospinal fluid leakage after transsphenoidal pituitary tumor surgery， and to investigate its predictive value.Methods A retrospective analysis was performed for the data of 56 patients who underwent transsphenoidal surgery for pituitary adenomas in The First People’s Hospital of Chenzhou from May 2018 to September 2020， among whom 32 patients used modified pedicled nasal septal mucosal flap and 24 did not use such flap. Related factors for cerebrospinal fluid rhinorrhea after transsphenoidal pituitary tumor surgery were screened out.Results Cerebrospinal fluid rhinorrhea after transsphenoidal pituitary tumor surgery was positively correlated with age >65 years， tumor diameter >2 cm， intraoperative rupture of diaphragma sellae， and time of operation >120 minutes （all P <0.05） and was negatively correlated with the use of modified pedicled nasal septal mucosal flap （P <0.05）. Reoperation （95% confidence interval ［CI］： 1.205~859.886， P = 0.038）， tumor diameter >2 cm （95% CI： 1.371~375.766， P = 0.029）， intraoperative rupture of diaphragma sellae （95% CI： 5.351~14461.621， P = 0.005）， and use of modified pedicled nasal septal mucosal flap （95% CI： 0.001~0.371， P = 0.009） were the influencing factors for cerebrospinal fluid rhinorrhea after transsphenoidal pituitary tumor surgery. The receiver operating characteristic （ROC） curve analysis of the predicted value of the model obtained an area under the ROC curve of 0.971 （95% CI： 0.935-1.000）， with a sensitivity of 1 and a specificity of 0.882.Conclusions Reoperation， tumor diameter >2 cm， intraoperative rupture of diaphragma sellae， and the absence of modified pedicled nasal mucosal flap are the risk factors for cerebrospinal fluid leak after transsphenoidal pituitary tumor surgery， while the use of modified pedicled nasal mucosal flap can reduce the incidence rate of this adverse complication.