In this work, we present a newly three antimicrobial chitosan, 2-benzoxazinyl benzoic acid (BBA) and novel biopolymer of Chitosan-spiroquinazolinone (SQC) via coupling of chitosan with benzoxazinyl benzoic acid, for promoting the antimicrobial activity of inherent chitosan. Modification in the chemical structure of the synthesized product SQC was confirmed using FT-IR and UV analysis. The antimicrobial activities of Chitosan, and BBA compounds were expressively increased more than chitosan-spiroquinazolinone SQC. Minimum inhibitory concentration (MIC) of compound SQC was supposed at 50 μ g / m l against tested microorganisms except for B.cereus and C.albicans. The highest concentration of Chitosan would prevent the growth of Gram-+ve upto 99%. However, compound BBA recorded the maximum inhibition percentage versus Gram-+ve approximately 82%. The findings emphasized that the developed Chitosan-Spiroquinazolinone SQC may be blocker for antimicrobial activity to pure chitosan and BBA i.e, stop reaction if possible for actions of antimicrobial treatments.