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Aiming at the problem that it is difficult to monitor the negative pressure in the air distribution pipeline in real time and it is easy to lead to the decline of seeding performance in the process of precise seed adsorption of rapeseed rape pneumatic precision seed metering device, a synchronised monitoring system for the negative pressure in rapeseed rape multiline precision seeding pipeline based on virtual instrumentation technology was designed. Pressure sensor as a measuring element for real-time collection of negative pressure of main and branch pipelines, NI-9205 digital acquisition card as a data acquisition module, the electric valve was used to control the negative pressure of main pipeline, and the LabVIEW software was used for the conversion, real-time display, analysis, preservation, fault alarms of the pressure value and so on. The accuracy of the pipeline negative pressure monitoring system was calibrated, and the results showed that under the condition that the rotational speed of the seeding plate was 20~60 r/min, and the valve opening was 18.3%~33.5% (the static negative pressure of the main pipeline was 1000~3000 Pa), the monitoring value of the monitoring system and the measured value of the wind manometer were not more than 3.63%, and the coefficient of variation of the stability of the negative pressure was not more than 2.97%. Bench test showed that under the conditions of 20~60 r/min rotational speed of the seeding plate and 18.3%~33.5% valve opening (1 000~3 000 Pa), the negative pressure loss rate of the short-distance air distribution system with the cone-column and cone-column air distribution mechanism was not more than 18.99%, the coefficient of variation of the uniformity of the negative pressure of the branch was not more than 2.3%, and the relative deviation of the coefficient of variation of each row did not exceed 4.27%. The field test showed that when the rotational speed of the seeding plate of the seeding operation was 23.1 r/min, 34.2 r/min, and 44.5 r/min, respectively, the negative pressure loss rate was not more than 18.75%, the coefficient of variation of the uniformity of negative pressure in the branches was not more than 2.95%, and the relative deviation of the coefficient of variation of each row did not exceed 4.52%. The research can provide technical support for analyzing the mechanism of precise seed adsorption and stable transport in pneumatic rapeseed precision seed metering devices, as well as for optimizing and improving the layout of the air distribution pipeline.