In this paper, we developed a simple design and a detection method for AND logic gates by using aptamers, Cetyltrimethyl Ammonium Bromide (CTAB), and melamine and cyromazine to control the aggregation and dispersion of gold nanoparticles (AuNPs). First, Based on the fact that aptamer T31 can specifically bind with melamine, and CTAB immediately resulted in the aggregation of AuNPs, an AND gate was fabricated to find whether there was melamine. It also has a detection limit of 0.24 mg·L^-1 by the naked eye to detect melamine, and the limit of detection (LOD) by a spectrophotometer is 85 μg·L^-1. Second, with the adsorption of aptamer Tcy1 on AuNPs and the strong coordination of Tcy1 with cyromazine, the addition of cyromazine and CTAB immediately resulted in the aggregation of AuNPs, giving rise to another AND gate. It also has a detection limit of 0.17 mg·L^-1 by the naked eye, and the limit of detection (LOD) is 9.0 μg·L^-1 by spectrophotometer. So, these logic gates can be used to detect melamine and cyromazine in raw milk.