98%。The hydraulic performance of lateral lines plays an important role in the drip irrigation system design. The virtual emitters and finite element method were used to compute the head loss and the way to reduce computational errors was suggested by selecting certain amounts of elements in order to meet the need of drip irrigation design. Moreover, virtual emitter with finite element method could dramatically reduce element number needed so as to reduce computational efforts and storage demands by 95 and 98 percent for virtual emitter and virtual emitter average head loss.