The invention discloses a multi-branch-chain drug conjugate with the following structural formula (I) as shown in description or a pharmacologically acceptable salt thereof, wherein R is an organic center, POLY is polymer, L is a multivalent joint, T is a targeted molecule, D is an activator, q is any integer from 3 to 8, L is as shown in the description, * is a connecting point for the multivalent joint L and the targeted molecule T, # is a connecting point for the multivalent joint L and the activator D, % is a connecting point for the multivalent joint L and POLY, l is any integer from 2 to20, m and n are any integer from 0 to 10, T is iRGD, cRGD, tLyp-1, Lyp-1 or RPARPAR, and D is a camptothecin drug. Compared with a small-molecule anti-cancer compound, the conjugate has stronger inhibiting ability in tumors, and is suitable for solid tumor types which comprise colon cancer, breast cancer, ovarian cancer, pancreatic cancer, gastric cancer, glioma as well as sarcoma, cancers and lymphoma of breasts, ovaries, colons, kidneys, bile ducts, lungs and brains.