Disclosed is a slow release injection agent of anticancer composition containing 
nitrosourea drugs and synergistic agent, which comprises slow release microspheres and dissolvent, wherein the slow release microspheres comprise anti-
cancer active constituents and slow release auxiliary materials, the dissolvent being conventional dissolvent or specific dissolvent containing suspension 
adjuvant. The 
viscosity of the suspension 
adjuvant is 100-3000cp (at 20-30 deg C), and is selected from 
sodium carboxymethylcellulose, the 
nitrosourea drugs are selected from 
Carmustine, 
Nimustine or 
Fotemustine, the synergistic agent can be selected from 
tetrazine drugs such as Mitozolomide or 
temozolomide and  /  or 
anticancer antibiotics such as Adriamycin, Aclarubicin, 
Epirubicin, mitomycin or pidorubicin, the slow release auxiliary materials are selected from 
polyphosphate ester copolymers such as p(LAEG-EOP), p(DAPG-EOP), 
copolymer or blend of 
polyphosphate ester with 
polylactic acid, Polifeprosan, sebacylic acid and 
PLGA. The anticancer composition can also be prepared into slow release implanting agent, for injection or placement in or around tumor with a period of effective concentration maintenance over 60 days, as well as the 
treatment effect of appreciably lowering general reaction of the drugs, and improving the 
treatment effect of the non-operative treatment methods such as 
chemotherapy.