Intermittent demand forecasting faces challenges including sparse observations, cold starts for new items, and product discontinuation. Classical methods (e.g., Croston, TSB) lack generative foundations, while deep learning models require large-scale data and suffer from poor interpretability. This paper proposes TSB-HB—a hierarchical Bayesian model that jointly models demand occurrence (via Beta-Binomial) and nonzero demand size (via Log-Normal), leveraging hierarchical priors to enable partial pooling across items. This design preserves item-level heterogeneity while enhancing robustness in estimating sparse demand sequences. TSB-HB delivers calibrated probabilistic forecasts and maintains strong interpretability. Evaluated on the UCI Online Retail dataset and an M5 subset, it significantly outperforms baselines—including Croston, SBA, and TSB—achieving substantial reductions in RMSE and RMSSE. These results demonstrate its generalizability and practical utility for intermittent demand forecasting.