Progo’s river is one of the rivers which passes from the top of Temanggung city to Indonesia Ocean and has and important role in fulfilling partly water in Yogyakart. The purpose of this study is to find out the value of the plann flood discharge and compare the result of the calculation of the researcher with the consultant. The location of this research is located in Kamijoro Dam, Sendang Sari Village, Pajangan, Bantul, which is in the Progo River basin with an area 2203, 480 km2.The method used in is this study is the nakayasu’s synthetic unit hydrograph, but previously it must be calculated using the polygon thiessen method and log pearson III. The result of the analysis of 9 stations(Salaman, Magelang, Katerban, Brosot, Kalibawang, Grabag, Temanggung, Parakan, Muntilan)in 1998-2007 namely at the time of the return periode 50 years were got debit 1281,56 m3/second and the return periode of 100 years 1443,33 m3/second. Comparison that have been do from the result of the analysis of the researchers’ counts with the count of consultants have a smaller value compared to the count of consultants due to differences in the number of stations taken from the existing watershed.