The invention discloses long-acting antimicrobial regenerated cellulose fiber. The long-acting antimicrobial regenerated cellulose fiber is prepared mainly by use of the following steps: manufacturing a carbon nanotube/cellulose composite material with a one-way directional hole after performing one-way freeze-drying on a mixed solution formed by regenerated bamboo cellulose and carbon nanotubes, assembling silver ions into the carbon nanotube/cellulose composite material through a soaking method, and then reducing the silver ions in the carbon nanotube/cellulose composite material into nano-silver particles by use of hydrazine hydrate, thus finally obtaining the long-acting antimicrobial regenerated cellulose fiber disclosed by the invention. The long-acting antimicrobial regenerated cellulose fiber clads the nano-silver particles in the one-way directional hole, the nano-silver particles are small in particle size and uniform in particle size distribution; the nano-silver particles are firmly adhered in the carbon nanotube/cellulose composite material and cannot fall off after repeated washing and rubbing, and the regenerated cellulose fiber has the long-acting antimicrobial performance.