This ELISA kit uses Competitive-ELISA as the method. The microtiter plate provided in this kit has been pre-coated with Porcine Ang-Ⅱ. During the reaction, Porcine Ang-Ⅱ in the sample or standard competes with a fixed amount of Porcine Ang-Ⅱ on the solid phase supporter for sites on the Biotinylated Detection Ab specific to Porcine Ang-Ⅱ. Excess conjugate and unbound sample or standard are washed from the plate, and Avidin conjugated to Horseradish Peroxidase (HRP) are added to each microplate well and incubated. Then a TMB substrate solution is added to each well. The enzyme-substrate reaction is terminated by adding Stop Solution and the color change is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The concentration of Porcine Ang-Ⅱ in the samples is then determined by comparing the OD of the samples to the standard curve.