The invention relates to cancer therapy drug sustained-release injection containing gemcitabine. The injection comprises sustained-release microspheres and dissolvent, wherein, the sustained-release microspheres comprise active ingredients for cancer therapy and sustained-release auxiliary materials, and the dissolvent is special dissolvent containing suspending agent. The active ingredients for cancer therapy comprise antimetabolite of gemcitabine or antimetabolite selected from zalcitabine, emtritabine, galocitabine, ibacitabine, ancitabine, decitabine, flurocitabine, enocitabine, imidazoletabine, capecitabine, gemcitabine, fludarabine or cladribine, and / or antimetabolite synergist selected from phosphoinositide 3-kinase inhibitor, pyrimidine analogs and / or DNA repair enzyme inhibitor; the sustained-release auxiliary materials comprise polifeprosan, bi-fatty acid, decanedioic copolymer, polylactic copolymer and EVAc; the viscocity of the suspending agent is 100cp to 3000cp (at 20 to 30 DEG C) and the suspending agent is selected from sodium carboxymethyl cellulose. The sustained-release microspheres can also be produced into sustained-release implant, and by injecting or positioning the sustained release agent in tumor or tumor margin, the efficacy of non-operative treatment such as radiation treatment and chemical treatment can be enhanced.