Abstract: Drip irrigation is one of the most effective irrigation methods in water saving irrigation, and accurate calculation of the head loss in its trickle laterals is the basis for its design. Calculation of the frictional head loss has been basically formed into a unified understanding, but the trends of minor head loss have not yet come to an agreement due to the complexity of emitter forms and diversity of emitter layouts. To examine the effects of on-line emitters on the local flow resistance and flow characteristic of laterals, this study has conducted laboratory tests on two types of laterals with different emitters. Water flows in these laterals were simulated using a computational fluid dynamics (CFD) method, and verified with the experimental data. The results show that numerical simulations were in good agreement with the experimental data and they provide useful information for investigation of the minor loss of emitters. We have conducted simulations for nine different designs of laterals and examined the influence factors of minor loss coefficient under different flow regimes. Simulations reveal that in both the laminar and turbulent flow cases, the minor loss coefficient of laterals decreased with an increasing Reynolds number, and increased with an increasing cross-sectional area ratio of the emitter to the pipe. The ratio of minor loss to frictional loss was related to the spacing of emitters and emitter discharge. The head loss of laterals in laminar regime was relatively small and may be neglected in preliminary calculation. This study would help the hydraulic calculation of drip irrigation laterals.