In order to observe the efficiency of screening synthetic dyes in foodstuffs by using the fingerprint method, we added the synthetic dyes into chilli products to see whether the added dyes could be identified. Fig. 3 showed the multi-wavelength chromatographic fingerprints of chilli products unspiked and spiked with synthetic dyes. By comparing the fingerprint chromatograms of chilli products with or without synthetic dyes, the 16 synthetic dyes (except Sudan II and Sudan III) added into samples could be recognized from the fingerprints. It could be seen that some synthetic dyes (e.g. Fast garnet GBC base and Sudan yellow) could be recognized more easily at 450 nm, some (e.g. Sudan orange G and Para red,) at 490 nm, some (e.g. Citrus red 2, Sudan red G, Toluidine red, Sudan I, Scarlet pigment powder, Sudan red 7B, Sudan red B, and Sudan IV) at 520 nm, and some (Sudan blue 2 and Sudan Black B) at 620 nm. It was found that Sudan II and Sudan III could not be easily recognized from the fingerprints because of co-elution with natural pigments. But we still could see that the spiking of Sudan II and Sudan III made the relevant peak shape a minor change, which might indicate the presence of exogenous adulterated synthetic dyes at some extent.