The invention relates to a flax fiber yarn automatic production line and a production process thereof. The production line comprises a rail and a clamping mechanism, a feeding part, a first heckling part, a rotary part, a second heckling part and a material taking part are sequentially arranged in the moving trajectory of the clamping mechanism, the clamping mechanism comprises an upper clamping assembly and a lower clamping assembly, the feeding part comprises a guiding separating mechanism, a stirring delivery mechanism, a conveying mechanism, a screwing mechanism and a transferring mechanism, the clamping mechanism is stirred and delivered by the stirring delivery mechanism to the direction of the screwing mechanism, the lower clamping assembly continues to move along the rail in the stirring delivery process, the upper and lower clamping assemblies are separated up and down, flax drops downwards towards one end of the rail on the conveying mechanism, the downward end of the flax istransferred to the lower clamping assembly by the transferring mechanism, the lower clamping assembly moves to the screwing mechanism to cooperate with the upper clamping assembly to clamp the flax under the action of the screwing mechanism. By means of the production line, the technical problems that flax needs to be sorted manually before heckling is conducted to put flax on the clamping mechanism, the labor cost is high, the efficiency is low, and the flax amount is nonuniform are solved.