Abstract: This study develops surrogate models for a small reactor based on the Group Method of Data Handling (GMDH), a self-organizing neural network algorithm. A dataset was constructed using the computational results from a high-fidelity, three-dimensional RMC model. A power prediction surrogate model was trained, which takes axial three-section detector readings as input to predict 15-section power distributions. Concurrently, a k_eff prediction surrogate model was established using 25 modeling parameters as input. The power prediction model achieves a relative deviation mostly within 3%. By applying a piecewise polynomial fitting method, the resulting pellet-level power predictions show a relative deviation of less than 5%. The k_eff prediction model demonstrates a root mean square error (RMSE) under 36 pcm, with the discrepancy between its predicted uncertainty and RMC's statistical results being less than 18 pcm. This work serves as a valuable reference for applying surrogate models to core power prediction and uncertainty analysis.