A lyocell fiber tow washing device comprises a plurality of traction units used for traction and squeezing of a tow, washing units used for cleaning the tow and water collecting units used for collecting eluents. Each traction unit comprises upper driving rolls and lower driving rolls, the upper driving rolls and the lower driving rolls are arranged in an upper-lower mode, alternate with each other and are distributed in a broken line mode, and the upper driving roll at the tail end of each traction unit is provided with a driven roll closely attached to the upper driving roll; each washing unit comprises wedge-shaped overflow troughs installed below the corresponding upper driving rolls, the slant sidewalls of the wedge-shaped overflow troughs are attached to the tow in a parallel mode, the slant sidewall of each wedge-shaped overflow trough is provided with an overflow port, and openings of the overflow ports face downward; each water collecting unit comprises a water collecting tank arranged below the corresponding traction unit. The lyocell fiber tow washing device can be used for cleaning away NMMO in the tow so that the NMMO can be recycled. The lyocell fiber tow washing device saves space and water and facilitates the following process.