BACKGROUND In China, approximately 15% of tubal pregnancy patients treated with MTX eventually required surgery because the ectopic mass was ruptured; therefore, it is essential to develop a model to predict the risk of failure with methotrexate treatment in tubal pregnancy. MATERIAL AND METHODS In this research, 168 patients met the eligibility criteria, and 29 candidate risk factors for treatment failure were collected. Multivariable logistic regression analysis was used to analyze the factors, and a full model was developed. We used a multiple fractional polynomial model and a stepwise model to increase the reliability. Bootstrap resampling for 500 times was used to internally test the prediction model. The integral performance of the model depends on the evaluation of the nomogram, the discriminative performance by receiver operating characteristic (ROC) curve analysis, and calibration. RESULTS The model showed excellent discrimination and calibration. The area under the ROC curve for the prediction model, mfp model, and stepwise model were 0.879 (95% CI: 0.812-0.942), 0.872 (95% CI: 0.805-0.931), and 0.880 (95% CI: 0.817-0.949), respectively. At a cutoff value of ≥0.40, sensitivity was 60%, specificity was 91%, positive predictive value (PPV) was 81%, and negative predictive value (NPV) was 77%. The model provides a net benefit when clinical decision thresholds are between 0% and 40% of predicted risk. CONCLUSIONS This model indicated good accuracy in predicting methotrexate treatment failure for tubal pregnancy patients.