In Ethiopia small scale irrigation schemes play a vital role in improving the livelihoods of the smallholder farmers’. However, existing small-scale irrigation schemes face various problems related to operation and maintenance, water management and sustainability. This study was conducted to technical performance evaluation of selected Small Scale Irrigation Scheme in Arsi and Western Arsi Zone using irrigation performance indicators. For this two scheme selected were Bubisa from Lemu-Bilbilo district of Arsi zone and Koma Arba from Adaba district of West Arsi Zone. From the study conducted on Bubisa and Koma Arba irrigation scheme using performance indices such as conveyance efficiency (Ec), application efficiency (Ea), on farm water lost (ROR+DPF), storage efficiency (Es), overall efficiency (Eo) and distribution uniformity (DU) and finally identifying problems of the scheme. For these study three farmers’ fields located at head, middle and tail of the two irrigation scheme were selected. From the result, parameters like Ec, Ea, on farm water lost (ROR+DPF), Es, DU and Eo were 67%, 60.27%, 39.73%, 89.59%, 90.50%and 39.77%, respectively for Bubisa irrigation scheme and 78%, 62.25%, 37.25%, 82.33%, 92.78% and 48.70% respectively for Bubisa irrigation scheme. Water Use efficiency (WUE) of Bubisa and Koma Arba scheme were 4.59 and 3.05kg/m3. This means that the yield from one meter cube of irrigation water for Bubisa irrigation scheme was higher than that of Koma Arba irrigation scheme. Sustainability of Irrigation System of the Bubisa and Koma Arba schemes were decreased by 42.7% and 62.5%compared with the planned. Therefore, for the improvement of the irrigation system management and the irrigation practice frequent performance evaluation is very important and solves problems related to operation and maintenance, water management and sustainability.