In order to study the dielectric properties of nano-carbon fiber-reinforced concrete, and find the law of reflection and loss of nano-carbon fiber-reinforced concrete to electromagnetic waves, the waveguide method was used to test the dielectric properties of nano-carbon fiber reinforced concrete with a fiber content of 0, 0.1%, 0.2%, 0.3%, 0.5% in the frequency range of 1.7 GHz to 2.6 GHz constant. The effects of fiber content and frequency on the dielectric properties of nano-carbon fiber-reinforced concrete were analyzed from the aspects of relative dielectric constant real part, imaginary part and loss tangent.At the same time, the effects of nano-carbon fiber and ordinary carbon fiber on the dielectric properties of concrete materials with 0.3% fiber content were compared and analyzed. The test results show that: nano-carbon fiber can increase the real part and imaginary part of the complex dielectric constant and loss tangent of the concrete material, and enhance the loss ability of the concrete material to electromagnetic waves; the greater the amount of nano-carbon fiber, the stronger the dielectric properties of nano-carbon fiber-reinforced concrete and the greater the loss of electromagnetic waves; the effect of nano-carbon fibers on the improvement of the dielectric properties of concrete materials is stronger than carbon fibers.