The invention discloses a method for manufacturing knitted flax fabrics, which comprises the following steps of treatment of weft yarns before weaving, weaving on a machine, and after-treatment. Firstly, flax yarns between 28 and 42 n/1 are steamed in a steam box for 60 to 90 minutes at a temperature of between 90 and 100 DEG C, subjected to heat preservation for 50 to 60 minutes, and woven on a bodkin plain circular knitting machine between 16 and 18 GG, wherein the vehicle speed is set to between 10 and 20 rpm, and the yarn feeding tensile force is between 5 and 6 g; and secondly, fabrics are subjected to rope chromating, and the finished products - the knitted flax fabrics with a weight of 190 grams per square meter are finally obtained. Therefore, the flax fabrics woven by the circular knitting machine have the advantages of soft hand feeling, good elasticity and good air permeability; and the method effectively reduces tears of the fabrics during the weaving process of the circular knitting machine and makes weaving and looping formation become smooth, so that the method reduces the defective rate during the process of mass production.