In this study, a portable and quantitative immunochromatographic assay (ICA) was developed with a smartphone-based detection device as readout. The carboxyl group coated Fe 3 O 4 nanoparticles (MNPs) were synthesized by a one pot method and used as the labeled tracer. Initially, zearalenone monoclonal antibody (ZEN mAb) and MNPs conjugates were prepared and applied as the detection probe. MNPs probe produced brown band at the detection zone of the ICA. To increase the sensitivity, MNPs probe were used to enrich ZEN from sample solution, a portable detection device was designed and a user-friendly APP was self-written to quantify results. The cut-off value of the MNPs-ICA for ZEN in cereals was 2.5 μg/kg. The detection limit and quantification limit were 0.06 and 0.13 μg/kg, respectively. The recoveries ranged from 82.0 to 117.7%, with coefficient of variation from 1.3 to 10.6%. The parallel analysis results of 20 naturally contaminated cereal samples by LC-MS/MS showed that the proposed method has high accuracy. Moreover, the results of stability experiments revealed that the ICA products had a shelf life of up to 6 months. Although the feasibility is demonstrated using ZEN as a model analyte, this approach can be easily developed to be a universal analysis system and applied to detection of a wide variety of small molecule hazard factor. This study proposed a qualitative and quantitative analysis device for the food safety analysis. • MNPs was synthesized as the Ab-labeled tracer. • A portable, dual detection mode, multi-channel detection device was designed. • A user-friendly detection APP was self-programmed for quantitative analysis. • Magnetic enrichment was used to improve sensitivity and robustness of the method. • MNPs-ICA was developed to detect five zearalenone toxins in cereals.