Abstract: The invention discloses a method and device of dynamically configuring linear density and blending ratio of yarn by four-ingredient asynchronous/synchronous drafted, comprising: a drafting and twisting system, which includes a first stage drafting unit, a successive second stage drafting unit and an integrating and twisting unit. The first stage drafting unit includes a combination of back rollers and a middle roller. The second stage drafting unit includes a front roller and the middle roller. Blending proportion and linear densities of the four ingredients are dynamically adjusted by the first stage asynchronous drafting mechanism, and reference linear density is adjusted by the second stage synchronous drafting mechanism. The invention can not only accurately control a linear density change, but also accurately control color change of the yarn. Further, rotation rate of the middle roller is constant, ensuring a reproducibility of patterns and colors of the yarn with changing linear density.