Intensity and duration of rainfall are among the factors that are effective in the occurrence of floods and the increase in damages caused by them. The design storm, which is extracted from the intensity-duration-frequency (IDF) curves for the duration and period of specific returns, is very important in hydrological and meteorological studies. In many studies of the design storm Non-regional coefficients are used, without a doubt, using the data of synoptic stations of the country instead of the experimental coefficients of other countries will be more accurate. To determine the IDF relationships, after scanning and digitization of the rainfall graphs, the amount of precipitation was obtained in different continuities. Precipitation intensities were calculated in each continuity. The obtained set of statistics was fitted with several types of statistical distributions. The significance of the obtained distributions was evaluated using chi-square test. Log-Pearson type 3 distribution showed a better fit compared to other distributions. Finally, intensity-duration-frequency relationships and its coefficients were calculated based on station conditions and its curves were drawn for different return periods. In Ahvaz, Behbahan and Lali stations, the highest rainfall intensity in the 2-year return period with a duration of 10 minutes was estimated as 18.66, 19.85 and 33.50 mm/h, respectively. This value increases with the increase of the return period in the same continuity; but with increasing continuity in the same period, the return has a decreasing trend.