Abstract: Objective: To evaluate the predictive value of PI-RADS2.1 combined with ADC value and PSA-related parameters based on multi-parameter magnetic resonance imaging for prostate cancer(PCa) in the PSA 0-20 ng/mL transitional zone. Methods: The patients from January 2021 to February 2025 were retrospectively collected,and divided into the PCa group and non-PCA group.The patients' age,PI-RADS2.1 score,ADC value and PSA-related parameters were statistically analyzed.The differences in each parameter between two groups were analyzed,and the ROC curve was used to analyze the value of each parameter in predicting PCa.Four prediction models were established by combining meaningful parameters:PI-RADS2.1+ADC(Model a),PI-RADS2.1+PSAD(Model b),ADC+PSAD(Model c) and PI-RADS2.1+ADC+PSAD(Model d). Results: A total of 40 PCa patients and 87 non-PCA patients were collected.The differences in the age,ADC value,tPSA,f/tPSA,PSAD,and PI-RADS2.1 were statistically significant between two groups(P<0.01).The PI-RADS2.1,ADC value and PSAD were significant predictors in diagnosing PCa.Among the four diagnostic models established by the above three parameters,Model d had the highest diagnostic value(AUC=0.957). Conclusions: The PI-RADS2.1 score combined with ADC value and PSA-related parameters can increase the diagnostic value of PCa in the 0-20 ng/mL transitional zone,and among them,the combined diagnostic value of PI-RADS2.1,ADC and PSAD is the highest.