Abstract: The objectives of the present research were to studying the NO3 leaching from soil columns at different NO3 concentrations and water flux densities and to comparing the computer simulation results using numerical and analytical models with column-experiment data. Three water flux densities (0.0442, 0.0265 and 0.0189 cm min-1) and NO3 concentration rates (150, 00 and 600 mg L-1) were used. The used soil has a loamy sand texture. The results indicate that the first water application rate (0.0442 cm min-1) be able to leach the nitrate from soil columns. The nitrate concentration was differed according the nitrate application rate (71, 1 and 53 mg L-1, respectively), in which increasing nitrate application rate increased the nitrate concentration in the leachate. The other water application rates did not show a significant leaching of nitrate. Nitrate ion was moved through soil profile to the bottom of the soil column at the end of experiment for the first water application rate. The maximum nitrate concentration was detected at 29, 7 and 15 cm below soil surface for the three water application rates 0.0442, 0.0265 and 0.0189 cm min-1, respectively. This indicates that increasing the water application rate resulted in more movement of nitrate ion in soil profile. The numerical model (HYDRUS-2D) and analytical model (CXTFIT), successfully predicted NO3 leaching in the present experiment (r-values between observed and predicted data ranged from 0.992 to 0.999). The results are much closed and there is an agreement between the two models. The present column experiment is useful for assessing relative behavior of NO3 in soil at different water application rates and nitrate concentrations resulted in increasing the movement of nitrate ion out of soil profile into groundwater.