A simple diagnosis method for vertical profile of moisture is introduced. The input data is the total precipitable water (TPW) deliniated from Shibata's algorithm using the TRMM TMI data. First we used Liu(1986)'s formula to estimate the surface specific humidity from the TPW, then assuming the Smith(1966)'s formula, we can calculate the vertical moisture gradient coefficients l, one below 850 hPa and another above 850 hPa. The result is compared with the objective analysis datasets(ECMWF, NCEP and JMA). This simple method gives a quick analysis tool for moisture profile over the ocean.