Abstract: Accurate flow measurement in irrigation areas is a fundamental part in the collection, distribution, delivery and application of water resources. Flow-measuring devices are used for continuous measurement of discharges in open channels. Compared with other existing flow-measuring devices, flumes are more suitable for flow measurement in open channels and easier to be widely applied. Much research has studied different kinds of flumes, such as airfoil-shaped flow flume, water-measuring column with round head, cut-throat flume, long-throat flume, providing a variety of adjustments of the channels. But there is not much work attempting for small-size flume or flume set in the field to measure discharges of water inlet in the field. Agricultural irrigation metrology is still the weak link of current metrological work. Owing to large head loss of long-throat flume and complex hydraulic performance of cut-throat flume, short-throat flume is appropriate for water discharge measurement of inlet in the field, which needs to satisfy the requirements such as simple structure, cheap price, reasonable accuracy and low head loss. One of the most widely used open-channel short-throat flumes is Parshall flume. However, owing to high price and complex structure, Parshall flume is not the optimum choice for water discharge measurement of inlet in the field. Originated from Parshall flume, a kind of portable short-throat flume with a flat base for the field is an emerging technique developed for water discharge measurement of inlet in the field, which consists of entrance, throat and exit sections. Based on the principle of critical flow, taking the flume with the width of 51 mm, the length of 774 mm and the discharge of up to 36 L/s as study subject, the experiments are conducted under 18 working conditions to determine its hydraulic performance. Hydraulic performance of portable short-throat flume with a flat base for the field is obtained from experimental analyses on water surface profile, Froude number, specific energy, location of critical depth section and head loss. Regression analyses developed for upstream depth versus discharge under free flow condition and submerged flow condition are satisfying with the relative error of within 10%, which meets the common requirements of flow measurement in irrigation areas. By analyzing variation of Froude number and specific energy along the flume under different discharges, it is concluded that the section of critical depth under free flow condition is located at the position with a distance of 475-485 mm downstream of the flume entrance (Section 1), and that under submerged flow condition is located at the position with a distance of 505-515 mm downstream of the flume entrance (Section 1). It is pointed out that the section of critical depth is located at the end of throat section under the two outflow conditions, and the location of critical depth section under submerged flow condition is more towards the downstream direction in the throat section than that under free flow condition. And the minimum and maximum head loss of portable short-throat flume with a flat base for the field account for 6.70% and 12.10% of total upstream head, respectively. Equations of upstream depth versus head loss under free flow condition and submerged flow condition are fitted with the maximum relative error of -9.80%. Compared with the long-throat flume, head loss of portable short-throat flume with a flat base for the field was significantly less. Further, for the portable short-throat flume with a flat base for the field, head loss under free flow condition is less than that under submerged flow condition. The flume placed at water inlet in the field, which is convenient to measure discharges and not constrained by type, size and slope of channels, is practical and portable in the field.