Abstract: Compaction quality depends on compaction parameters (rolling speed, vibration status, rolling passes, and compacted thickness) and material parameters (moisture content, uniformity coefficient, and curvature coefficient). Real-time compaction parameters at any location can be obtained using real-time quality monitoring technology of rockfill dam construction. The material parameters, however, are uncertain and difficult to be monitored in real-time, which results in an uncertainty in compaction quality evaluation. Based on the pit sampling data, this paper establishes a nonlinear mapping relationship between input (compaction parameters and material parameters) and output (dry density). Therefore, the dry density at any location of the entire rolled working unit can be fitted using real-time compaction parameters and material parameters (generated by improved Bootstrap method) as input. Results show that dry density, when fitted with compaction parameters as input, is greater and more concentrated than its real value. After adding the material parameters in the input, however, the dry density is more dispersely distributed and has a greater uncertainty, which gives a more objective fitting and reduces the sidedness of pit sampling and compaction parameters control.