The　public　health　concern　of　antibiotic　residues　in　animal-origin　food　has　been　a　long-standing　issue.　In　this　work,　we　present　a　novel　method　for　antibiotic　detection,　leveraging　optical　weak　value　amplification　and　harnessing　an　indirect　competitive　inhibition　assay,　which　significantly　boosts　the　system＇s　sensitivity　in　identifying　small　molecule　antibiotics.　We　chose　chloramphenicol　as　a　model　compound　and　mixed　it　with　chloramphenicol-bovine　serum　albumin　conjugates　to　bind　to　the　chloramphenicol　antibody　competitively.　We　achieved　a　broad　linear　detection　range　of　up　to　3.24　ng/mL　and　a　high　concentration　resolution　of　33.20　pg/mL.　To　further　validate　the　universality　of　our　proposed　detection　methodology,　we　successfully　applied　it　to　testing　gibberellin　and　tetracycline.　Moreover,　we　conducted　regeneration　experiments　and　real-sample　correlation　studies.　This　study　introduces　a　novel　strategy　for　the　label-free　optical　sensing　of　small　molecule　antibiotics,　greatly　expanding　the　range　of　applications　for　sensors　utilizing　optical　weak　value　amplification.