The invention discloses a chitosan derivative containing a quinazoline ring as well as a preparation method and the biological activity, namely, the compound shown in the general formula (I) and the preparation method of the compound. In the general formula (I), R1, R2, R3, R4 and R5 have definitions in the specification. According to the invention, the chitosan derivative containing the quinazoline ring is synthesized through reaction taking 4-chloroquinazolines or 4-chloroquinazolines substitution and chitosan as raw materials, and taking a mixed solution of methyl alcohol, ethanol, normal propyl alcohol, isopropyl alcohol, normal butanol, isobutanol, tertiary butanol, isoamyl alcohol, neopentyl alcohol, pentaerythritol and water as a solvent. The partial compound has the proliferation inhibition effect for the tested mouse gastric carcinoma cell MFC and the human breast cancer cell A549, and shows certain anti-cancer activity.