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Aiming at the problems of complicated folding and unfolding process, poor synchronous coordination and the obvious mechanical vibration of traditional mechanical spray rod, a spraying rod consisted of single cylinder multiple folding mechanism was designed combined with the agronomic characteristics of paddy field plant protection in Northeast China. The structure and working principle of the spraying rod with multiple folding mechanism were expounded and analyzed. The length of each part was determined according to analytic method. Through orthogonal experiment and virtual simulation technology, the effects of various types of steel pipes with different wall thicknesses on spray rod quality and firstorder natural frequency were investigated, and the results were analyzed and optimized by DesignExpert 8.0.6 software. The optimization results showed that when the wall thickness of round steel pipe, rectangular steel pipe and square steel pipe was 2mm, 2mm and 2mm respectively, the mass was 62.85kg, which was the lightest and the dynamic characteristic was good at this point. Its first order natural frequency was 14.84Hz, which avoided the 13.03Hz of the pavement incentive frequency. The finite element model of the sprayer was established by ANSYS-workbench software and the numerical modal analysis was carried out. The first four order nonzero modal frequency and vibration mode of the sprayer were solved, and the accuracy of the numerical model optimization results was verified by modal test. Field experiments showed a stable performance of the machine, uniform spraying of liquid pesticide solution, good coverage, and no obvious vibration of spraying lever during operation.