Pesticides have played a significant role in crop diseases and insect pests, as well as high and stable yields of crops, but the long-term large-scale use of pesticides has caused great harm to ecology and human health. According to the relevant literature review, there are no related reports on the detection of pesticide residues based on the analysis methods of immunosensors and laser-induced breakdown spectroscopy. In this method, a laser-induced breakdown spectrum is proposed to detect the probe of the immunosensor capturing the target to be detected, there by indirectly calculating the concentration of the target to be measured. This article uses immunochromatographic test strips to detect trace pesticides. Although immunochromatographic test strips can measure trace pesticides, they can only be qualitative, and the detection range is narrow. In order to broaden the measurement range of trace pesticides by immunochromatographic test strips, laser-induced breakdown spectroscopy (Laser-induced Breakdown Spectroscopy, LIBS) was used to perform spectroscopic measurements on metal nanoparticles captured trace pesticides on immunochromatographic test strips. Construction of detection methods for immunochromatographic test strips and LIBS. In this paper, chlorpyrifos pesticides are used as the research object. Because pesticide residues are small molecule antigen detection, the immunochromatographic test strips use the competition method to detect chlorpyrifos. The color difference between the control line and the detection line of the immunochromatographic test strip with a low concentration of chlorpyrifos dripped is not obvious, and human eyes cannot distinguish whether chlorpyrifos is detected. The control line and detection line of the immunochromatographic test strip added with chlorpyrifos were selected respectively, and the spectrum at Au Ⅰ 242.733 nm was measured. The average spectral intensity of the control line minus the average spectral intensity of the detection line is the signal of chlorpyrifos. This method can detect signals not observed by immunochromatographic test strips, and avoid the problem of high detection limit of LIBS. As the chlorpyrifos concentration increased from 0 to 10⁶ ng·mL^-1, the difference in LIBS spectral data gradually increased. In order to eliminate the effect of random errors, a calibration curve was constructed using △LIBS intensity (measurement sample intensity minus blank sample intensity) and chlorpyrifos concentration to obtain Lg. △LIBS intensity was linearly correlated with chlorpyrifos concentration in the range of 10~10⁶ ng·mL^-1, Y=6.14X+31.85, R²=0.969, and the detection limit of chlorpyrifos was 0.39 ng·mL^-1. The results showed that the immunochromatographic strip combined with LIBS could effectively expand the detection range of chlorpyrifos. At the same time, the combination of immunochromatographic test strips and LIBS for the detection of other substances is also worthy of further research.