Using three-dimensional tomographic imaging results of 2°×2°grid S wave velocity and 15′×15′ grid average gravity anomaly in North China,this paper adopted inversion with constrained least squares method and,as a result,obtained density distribution results of six bedding surfaces in lithosphere of North China.The inversion results indicate the following phenomena: the lithosphere density beneath North China area is extremely inhomogeneous,which is the reflection of the feature of violent tectonic movement;the density distribution is coherent with tectonic;the density is different in different tectonic units;there are low density regions in the crust;the strong earthquakes in North China region mainly occur at this depth.