The present research was carried out to determine the best lateral length of micro-irrigation systems using a mathematical model of Microsoft Matlabversion 10.0. The program models were designed to find a discharge variation (10, 15 and 20 %) and uniformity of emission (UE) of more than 80 %. After that, the experimental field included three emitter devices for validating the mathematical program. The examined test emitter devices were on-line (Em_on), built-in (Em_in) and micro-tube (Em_mt, 3.82 mm internal diameter with 25 cm length), three different length lengths (20, 40 and 60 m), at five operating head pressures (40, 60, 80, 100 and 120 kPa). The comparison between mathematical models showed a very agreement with the experimental validation. The experimentally obtained results have a strong relationship with the determination coefficient (R²) ≥ 0.9512 between the calculated and predicted UE for Em_on and Em_in. This relationship was decreased with R² about 0.8082 for Em_mt at different treatments.