The invention relates to an automatic powder spraying line for automobile wheel hub finishing components and a technique thereof; the production line comprises a pure water filtration system for providing pure water for the power spraying line, a pretreatment device, a pretreatment water content drying device, an automatic dust blowing device, an automatic powder spraying device, a solidifying device and a conveying lead rail; wherein, the pretreatment device sequentially comprises a pickling tank, alkaline wash tank and a passivation tank; the automatic powder spraying device comprises a tank body, a powder spraying gun, a powder storage tank, a powder sucking device, a constant temperature and humidity device. The production technique has the following steps: 1) alkali degreasing, 2) product surface cleaning, 3) drying, 4) dust abatement, 5) power spraying, 6) solidification. The production line of the invention features high degree of automation, suitability for mass production, high output benefits and low cost; in addition, the production technique equipped with the production line is more reasonable, components produced by the coating method of powder spraying has more uniform surface color and thickness.