This kit is based on competitive indirect immunochromatography technology, in which pendimethalin in sample competes for the colloid gold labeled antibody with pendimethalin coupling antigen captured on test line to cause the change of color of the test line. The color of Line T is deeper than or similar to Line C, indicating the pendimethalin in sample is less than LOD of the kit. The color of line T is weaker than line C or the line T no color, indicating pendimethalin in sample is higher than LOD of the kit. Whether the pendimethalin exist or not, line C will always have color to indicate the test is valid.