To solve the problem of low selectivity of current immunochromatographic assay (ICA) for aflatoxin B(1) (AFB(1)) alone detection, a novel selective ICA was developed here. With very high selectivity, a new AFB(1) monoclonal antibody (MAb) 3G1 was prepared by immunizing Balb/c mice with aflatoxin B(2a)-BSA (AFB(2a)-BSA) rather than AFB(1)-BSA used in other reports and 3G1 possessed the highest selectivity than those used in published ICAs. The ICA with visual detection limit (VDL) of 1 ng mL(-1) showed no cross-reactivity with other aflatoxins. Comparing with previous reports, the ICA here provided the most powerful guarantee for avoiding false positive results leaded by coexistence of other aflatoxins in samples. For validation, naturally contaminated samples including peanut, puer-tea, vegetable oil and feedstuff were respectively assayed by ICA and a standard high performance liquid chromatography (HPLC), and good agreement of results was obtained between two methods. Therefore, the developed ICA could well meet the selective detection of AFB(1) in agro-products.