The invention discloses a flax blended knitting yarn and a production process thereof. The process comprises the following steps of: (1) mixing raw materials: firstly spraying an emulsion onto a flax raw material, storing for 24 hours, mixing the flax raw material with modal fibers at a blending ratio of 15/85 to 85/15 by use of a weighing and mixing method; (2) fore-spinning, namely opening picking, performing cotton carding, and drawing; and (3) performing a rotor spinning process, namely carding at a carding roller rotation speed of 10000-6000r/min under conditions that the temperature of 25 DEG C and the relative humidity is 75 percent, spinning by virtue of a spinning cup with diameter of 48mm-64mm at a spinning cup rotation speed of 40000-50000r/min, twisting at a twist coefficient of 340-390, leading yarns at a speed of 58.5m/min with tension draft of 0.98, and performing water washing sorting, namely performing water washing sorting on the blended knitting yarns at a temperature of 40-50 DEG C, wherein a lotion contains 7-9mmol/L magnesium chloride and valine at a molar ratio of (6-8):1; and performing setting treatment, namely performing setting treatment on the blended knitting yarns washed with water at a temperature of 110-120 DEG C.