The invention discloses a dielectric characteristic detection device for electric small-scale samples based on near zero transmission. The dielectric characteristic detection device is an asymmetric three-port network, and specifically includes a bottom metal layer, an intermediate dielectric layer and an upper metal strip. The upper metal strip includes a micro-strip Wilkinson power divider, a 90-degree 3dB branch line coupler, two branches, and electric field enhancement stubs loaded on the two branches. The two electric field enhancement stubs constitute the test and reference areas of thedielectric characteristic detection device, and micro fluid passages are loaded in the test and reference areas respectively. When the two micro fluid passages are loaded with the same sample or the device is in a no-load state, the dielectric characteristic detection device will be in a symmetrical balance state, and there will be two transmission zeros. When there is a small difference between the samples loaded by the micro fluid passages, the transmission zero of the dielectric characteristic detection device will change. The device of the invention has the advantages of convenient use, low price and easy integration.