The invention belongs to the technical field of pharmaceutical preparations and particularly discloses a combinative-administration thermotropic gel sustained-release injection and a preparation method thereof. The thermotropic gel sustained-release injection is composed of a Pt(IV)-containing amphipathic segmented copolymer, taxane drugs and a solvent. By thermotropic gelatinization phase transformation along with temperature rise, physical hydrogel is formed spontaneously; the amphipathic segmented copolymer is formed by polyethylene glycol serving as a hydrophilic segment and degradable polyester serving as a hydrophobic segment, and functional groups can be connected to the tail end of the segmented copolymer. The gel sustained-release injection has advantages that release periods of platinum type antitumor drugs and taxane drugs can be remarkably prolonged, and synergistic release of the platinum type antitumor drugs and the taxane drugs can be realized; the injection is availablefor intratumoral, peritumoral and postoperation intralesional application by means of injection, and after in-vivo in-situ gelatinization of the injection, the bonded platinum type drugs and the coated taxane drugs can be slowly released from gel, and accordingly administration frequency and whole-body toxic and side effects can be reduced.