The invention discloses a production method of a blended yarn. The production method comprises the following steps of mixing Baicao silk and jute fiber and Sanyou color fiber, and preparing into mixed card sliver through an opening picking process and a cotton carding process and a carding process; carrying out a blowing-carding process and a combing process on cotton fiber to obtain combed sliver; carrying out three drawing processes, a roving process and a spinning process on the mixed card sliver and the combed sliver to obtain the blended yarn. Through the manner, according to the production method of the blended yarn, the zinnia silk jute fiber, the Sanyou color fiber and the cotton fiber are prepared into the blended yarn with favorable yarn forming quality, so that a fabric is smooth, soft, skin-friendly, bright in color, humidity-absorbing and breathable, realizes skin care, and has silky luster, plant antibacterial property, a unique style and high added value, a yarn formation structure is optimized, the yarn quality is better, and the popularization of the production method of the blended yarn has a wide market prospect.