A framework of Human Error Probability (HEP) parameters is first proposed, which is needed for Human Reliability Analysis (HRA) within a practice of Probabilistic Safety Assessment (PSA) of Nuclear Power Plant (NPP). Then, a laboratory experiment has been conducted for constructing a computer simulation model (human model) which describes human cognitive behavior on detecting and diagnosing plant anomaly cause. Inter-comparison between experimental data and human model simulation has been made to estimate Human Cognitive Reliability (HCR) curves , in order to confirm the applicability of human model for estimating such HEP parameters for PSA/HRA practice.