The present invention relates to an inkjet printing ink which has good color developing property and fastness and a broad color gamut in printing various textile materials such as polyesters, cottons, silks, nylons, etc., knitted materials, particularly mixed fibers so that the product value of printed fiber products including garments can be increased, a process for preparation thereof, and a printing method using said ink. Moreover, the present invention provides an ink for inkjet printing suitable for polyester ultrafine microfibers and nylon/polyester ultrafine microfibers.