Optimizing the use of irrigation water is vital importance in conserving land and water resources as well as maximizing yield with the available water. Evaluating an irrigation system performance should measure and show the effectiveness of existing irrigation practice provide remedial measures if necessary, as well as determining the impact of the factors which affect the performance parameters. The aim of this study was to evaluate and assess Performance of Quashni irrigation Scheme using internal performance indicators (conveyance efficiency, application efficiency, and overall scheme efficiency) and External performance indicators (water use performance indicators which include RWS and RIS and physical performance indicators include irrigation ratio). Primary data was collected in the upper, middle and downstream users of three farmer’s field in the first season and nine farmers field in the second irrigation season. Primary data (Soil moisture before and after irrigation, discharge measurements, irrigation depth and soil physical properties were collected. Secondary data (meteorological data and irrigated area per crops) were collected from Dangila Woreda Bureau of Agriculture. CROPWAT 8.0 computer model was used to calculate the crop water requirements. The main and secondary canal conveyance efficiency was 76.1 and 67.5% respectively. Application efficiency during the first and second irrigation seasons 55.5 % and 47% respectively with average application efficiency 51.2% of the scheme. Therefore overall scheme efficiency was 36.8%. RWS and RIS of the scheme were 1.24 and 1.12 respectively. Irrigation ratio of Quashni irrigation scheme was found to be 0.84 which means 16% of the command area was not under irrigation during the study period. In general based on evaluation and assessment carried out performance of Quashni irrigation scheme is low. to Maximize efficiency and sustain the scheme ; it is recommended that all activities in the irrigation network should be monitored and checked, technical requirements should be met, training and extension should be enhanced, evaluations should be performed on a seasonal basis and the results should be delivered to the relevant individual and institutions with an efficient monitoring and evaluation system.