Abstract: With the rapid development of integrated circuit, the RC delay caused by the increase of device density and wire density and the decrease of line width became the biggest problem for the reliability of interconnect wires. It is reported that the application of low-k material is the important measure to reduce RC delay, crosstalk and power dissipation. In order to adapt to the development of high speed and high integration for ULSI, the exploration for low-k material is the inevitable choice for integrated circuit.This paper systematically introduces the characteristics, classification and the methods to reduce k value of low-k material. Here taking the inverter circuit as example and using the AFD principle to calculate the AFD value for different low-k materials. It can realize the quantitative analysis of the impact for different low-k materials on the circuit reliability.