In this study by data of synoptic stations in Karoon basin، the intensive showers with 1،2،6 and 9 hour duration have been extracted and the precipitation time regime has been evaluated by ranking method and non dimensional accumulation curve. In ranking method، first the showers of each time base have been divided to smaller periods and on this basis different periods of showers have been ranked according to the amount of received precipitation. In accumulating curve method، the showers of all specific time bases have been depicted in non dimensional form and the regression line as a representative and the mean of all the showers has been implemented. The results of two mentioned methods show that the peak of shower precipitation occurred in 25 percent of first time and 25 percent of second time of precipitation. This means the dominant structure in the chosen time bases in the studied basin are the first and second quarter of showers.