Abstarct: Poor performance of irrigation and drainage network is o serious concern to governments. Tangible reality of the world is that most irrigation and drainage projects implemented worldwide have not fulfilled their aims and in some cases have faced with difficulty. Equipping and modernization of irrigation systems and irrigation networks, water and agricultural sector is one of the main pillars o national resources. Every year much o expenditures of national resources are being spent on irrigation systems and associated facilities such as diversion dams, dewatering and water turns for somewhat water usage can be controlled and optimized. But it is noteworthy that if any problem occurs and if the network is not resolved, over time the utilization o the irrigation and drainage network will face of with problems. Not only soil and water conservation led to the destruction of these resources. Therefore it is necessary to evaluate the technical performance of hydraulic irrigation and drainage canals. The aim of this study is the technical performance of hydraulic channels of Semnan which pilot irrigation and drainage of Garmsar was chosen. In this regard, the first field visit conducted was recording the problems, and then necessary measurements were done. The results showed that problems such as sedimentation in canals, the weed growth in berm of canals, improper sealing contraction joints in the body of canals, longitudinal and transverse crack in some canals, concrete degradation at raphs, sediment filling in check drops, improper performance of neyripic gates and etc. are of the most important network failure of Garmsar. Network transmission efficiency is a measure of performance measurement which was calculated in this study and was estimated 89% which is considered as goof baxsed on the solids in the water network the term turbidity was used for the first time and the relation between the turbidity and suspended solids concentration were obtained for these networks which will be used in estimation of suspended load in the network and in sediment management is useful. According to the hydraulic calculations subcritical flow was removed in section and the design is good.