A method of reconstructing the nanosecond signal is carried out based on Labview. A standard nanosecond pulse is got from pulse generator, and then the pulse is measured with a voltage divider. Through model identification, the math expression of the divider can be get. The best order of the filter is got simultaneously. The study of reconstructing input signal of measurement system is carried out. The result shows that the measurement system can be compensated well based on the math model, and it achieves the prospective objective.