As an important oil crop in the north of China, the demand for flax had been increasing in recent years. Due to drought and little rain in flax growing area, the yield reduction caused by various diseases, insects and weeds is very serious. However, flax plant protection in arid areas was mainly manual operation or used relatively mature spraying machinery such as wheat and corn. The 3WYP900 type of dryland beard spraying machine was designed for the current dryland beard mechanized spraying operation with low operational efficiency, few supporting models, low degree of automation, mist on the operator injury and other problems, which could realize remote control and skid steering. The key components of the prototype walking steering device, spraying device, spraying rod lifting and folding device were designed and theoretically analyzed and calculated in combination with operational requirements. Different spray nozzle application pressure was set for spraying and spray width test, the test results showed that when the pressure was 0.3MPa, a single spray nozzle coefficient of variation was minimum (coefficient of variation of 0.0096) with the best stability, and the pressure under the most stable spray width (spray width of 9.423~9.622m). In the 0.3MPa pressure occurred under the number of dripping nozzle were less than 3, the maximum volume of a single nozzle was 3 drops, the total number of drops of dripping liquid was 5, antidrip performance was in line with national standards. At the same time, the machine speed steering and braking flexibility, control feedback accurate and rapid, no rollover during the test, stall, spraying interruptions and other phenomena, indicating that the basic machine can meet the design requirements, with the relevant conditions of the field test. The research result could provide reference for the whole mechanization of dryland flax. 