Abstract: Pile load tests, including static load test, dynamic load test , are often used to interpret the pile capacity. Among these tests, static load one is conducted commonly. It requires a lot of labor work and expense, and the installation causes danger. The test data sometimes is incomplete and unavailable for interpreting the capacity. This study uses wave equation analysis to model pile load test and iteration method to modify nonlinear material properties from SPT-N values. The test data is modeled and extrapolated to make easy access from the interpretations. Results are verified with the field data and other predictions.