The Lucovsky equation and the position detecting formulation of PSD under stable situation are briefly introduced.With the instance of Duo-lateral PSD,a position detecting effect gridding chart of PSD based on the stable situation formulation and under the excitation of very-short-pulse illumination is showed.Pointing to the problem of a bad linearity,an integral detecting method is worked out.And the position detection effect gridding chart based on this method and under the excitation of very-short-pulse illumination is showed too.From the chart we can obviously see that it provides a very high precise to adopt the integral method on the PSD detection.