For the domestic food safety problem that caused by the pesticide residues in food, it’s very important to find a convenient and cost-appropriate detection technology. At present, spectroscopy absorption technology has been used for detection of pesticide residues in food. However, there are some deficiencies such as the quantitative detection and the measurement precision. This experiment that based on differential absorption is completed by using miniature fiber optic spectrometer and spectrophotometer, and then the pesticide DDVP is also measured quantitatively. Thus the pesticide residue detection technology that based on spectroscopy absorption is improved to adjust to the practical application.