Surface enhanced infrared absorption spectroscopy is a promising analytical technique and has been widely used in many fields recently. The key to the SEIRAS spectroscopy lies in the preparation of substrate with infrared enhancement effect. However, the cost, process steps and consuming time of the SEIRAS substrate preparation method have yet to be optimized. Metal materials are usually difficult to be used as support materials for transmission SEIRAS (T-SEIRAS)substrates due to its opacity. In this study, we innovatively used copper foam materials with a three-dimensional pore structure as support materials and loaded silver nanoparticles on copper foam based on improved displacement reaction principle. A fast, simple and low-cost method for preparing T-SEIRAS substrate was developed in this research. The dosage of surfactant and reaction time were optimized. The results showed that when the dosage of silver nitrate (0.2 mmol·L-1) was 10 mL, the dosage of Polyvinylpyrrolidone (PVP) (0.05 g·mL-1) was 2 mL and the reaction time was 30 s, the infrared enhancement effect of the substrate was optimum. The characterization of SEIRAS substrate by scanning electron microscopy (SEM) and X ray photoelectron spectroscopy (XPS) showed that silver nanoparticles, from tens to one hundred nanometer, were successfully loaded on the Cu foam. The optimized AgNPs-Cu foam SEIRAS transmission substrate could significantly enhance the infrared signal of the probe molecule 11-mercaptoundecanoic acid (MUA) and the thiram pesticide. Its enhancement multiple of MUA at 1 689 cm-1 is 32.7 times, and 2.9 times of thiram at 1 371 cm-1. Linear fitting of absorption signal intensity at 1 236, 1 371, 1 495 cm-1 and the concentration of thiram was investigated. Linear optimum was found at 1 236 cm-1 with a correlation coefficient of 0.923. The detection limit of thiram was 0.024 mg·mL-1. The experimental results of this study provide a new scheme for the rapid and simple preparation of SEIRAS transmission substrate and a new idea for the rapid on-site detection of thiram pesticide.