Abstract: Two haptens of MCPA(M), 6- hexanoic acid (MC) and 4- butanoic acid(MB) were synthesized with MCPA and amino-hexanoic acid or amino-butanoic acid. These two haptens and MCPA were conjugated to bovine serum albumin (BSA) with the modified active ester method, respectively. Three coating antigens, M-OVA, MC-OVA and MB-OVA were also synthesized with the mixed-anhydride method, respectively. As a result of the study, three types of antibody (named M-Ab, MC-Ab and MB-Ab) were produced successfully. Their titers were as follows, 1.0×106,1.2×106 and 2.0×106, respectively, while the concentration of coating antigens was 4 μg/mL. Among these antibodies, the M-Ab was only adapted to detect the herbicide with homologous assays, the linear detection ranged well from 0.01 mg/L to 10mg/L(IC50, 1.3 mg/L) and the limit of detection(LOD) was lower than 0.01 mg/L.