Disclosed is an anticancer slow release agent which comprises slow release microspheres and dissolvent, wherein the slow release microballoons comprise anti-cancer active constituents and slow releaseauxiliary materials, the dissolvent being specific dissolvent containing suspension adjuvant. The anticancer antibiotics are selected from Idarubicin, Valtaxin, Pirarubicin and Mitoxantrone, The anti-metabolite drugs are selected from Pemetrexed, Carmustine, Tegafur, Zalcitabine, Emtritabine, Galocitabine, Ibacitabine, Ancitabine, Decitabine, Flurocitabine, Enocitabine, Imidazoletabine, Capecittabine, Gemcitabine, Fludrarbine, Raltitrexed, Dexrazoxane, Cladribine, Nolatrexed and folic acid, The slow release auxiliary materials are selected from EVAc, Polifeprosan, sebacylic acid copolymer, lactic acid, the viscosity of the suspension adjuvant is 100-3000cp (at 25-30 deg C), and is selected from sodium carboxymethylcellulose. The slow release microspheres can also be prepared into slow release implanting agent for injection or placement in or around tumor.