In this study, Taguchi quality engineering was used to improve the washing effectiveness of regenerated cellulose filaments. Using an experimental design based on an L27 (34) orthogonal table, post-drying fiber tenacity was analyzed to evaluate the effects of various factors, develop an optimized water washing parameter design, and improve finished fiber washing effectiveness. The application of the proposed method increased the multifilament strength and Taguchi signal-to-noise (S/N) ratio by 8.22 and 4.64%, respectively. Using the proposed approach, the desired characteristic values could be predicted, and the S/N ratio was used to directly derive a quality characteristic stability index.