Abstract: According to the shortage of resoarch work on pressure loss in pressure regulation device of complete fluidic sprinkler for variable irrigation, the pressure variation of system was analyzed by Bernoulli equation. Based on definition system characteristics the sprinkler changed when working. The loss pressure coefficient was put forward with the value that, plus of section area variable coefficient and shape coefficient and then minus axial clearance influence coefficient of the moving chips in relative motion. For the calculation, the maximum loss pressure coefficient value was 0.7414, the minimum value was 0.0204. Virtual instrument and LabVIEW software were adopt to measure the relationships between pressure value, the sprinkler running time, the working conditions of pressure regulation device. The results showed that when the flow rates decreased, the upstream pressure increased, and the downstream pressure decreased, the range of downstream pressure changed was larger relatively. With the flow rate decreased, the loss coefficient increased. The maximum loss coefficient value of pressure regulation device was 0.582, and the minimum value was 0.265. The study can provide a theoretical basis for the design of complete fluidic sprinkler pressure regulation device.