The invention discloses a high-power aluminum nitride ceramic substrate 100W-20dB attenuator, which comprises an aluminum nitride substrate, a conductive layer is printed on the back of the aluminum nitride substrate, and several resistors and silver are printed on the front of the aluminum nitride substrate. Paste wire, the silver paste wire is connected to the resistor to form an attenuation circuit, and the glass protective film is printed on the resistor. The high-power aluminum nitride ceramic substrate 100W-20dB attenuator increases the resistance area, increases the high and low temperature impact resistance of the attenuator, and makes the product performance index meet the requirements. At the same time, it avoids the high temperature resistance quenching when welding the lead wire at the output end, avoids the risk of damage due to resistance quenching during actual use, and improves the circuit design so that the product can be applied to 3G networks.