Multiple-mycotoxin contamination has been frequently found in the agro-food monitoring due to the coexistence of fungi. However, many determination methods focused on a single mycotoxin, highlighting the demand for on-site determination of multiple mycotoxins in a single run. We develop a multicolor-based immunochromatographic strip (ICS) for simultaneous determination of aflatoxin B1 (AFB1), zearalenone (ZEN) and T-2 toxin in maize- and cereal-based animal feeds. The nanoparticles with different colors are conjugated with three monoclonal antibodies, which serve as the immunoassay probes. The decrease in color intensity is observed by the naked eyes, providing simultaneous quantification of three mycotoxins. The visible limits of detection for AFB1, ZEN and T-2 are estimated to be 0.5, 2, and 30 ng/mL, respectively. The cut-off values are 1, 10, and 50 ng/mL, respectively. Considerable specificity and stability are found using real samples. The results are in excellent agreement with those from high-performance liquid chromatography/tandem mass spectrometry. The multi-color ICS boasts sensitive and rapid visual differentiation and simultaneous semi-quantification of aflatoxin B1, zearalenone and T-2 toxin in maize- and cereal-based feed samples within 20 min.