The origin of silks remains one of the most puzzling mysteries. However, the on-site identification of ancient silks usually becomes particularly difficult after thousands of years due to degradation and sample contamination. In this paper, a portable immunochromatographic strip (ICS) technique using colloidal gold-labelled polyclonal antibody was well designed and developed. This technique requires only 10 min to complete the qualitative detection of silks. The strip exhibits good sensitivity, specificity and thermal stability. The detection limit of the strip is 1.5 μg mL⁻¹, and no cross-reactions with other possible interfering antigens were noted. Moreover, the strip can maintain the effectiveness after being treated at 60 °C for 30 days. These characteristics make the ICS assay especially suitable for the on-site detection in the archaeological field.