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利用傅立叶分析法分离出河西──祁连山地区重力变化的长波项和短波项，进而推导出重力场所产生的散度场计算公式，分别计算出各时段的重力散度值，绘制出重力变化的长波项和短波项及散度等值线图。并结合该地区的地震活动和地壳深部构造资料进行综合分析研究，初步得出以下认识：①重力非潮汐变化的长波项是由地壳深部物质迁移所引起，具有NW向特征，与区域构造运动的继承性有关，通常把它作为地壳运动的正常值；②重力非潮汐变化的短波项是由地壳浅部因素引起，其图像特征与区域构造活动密切相关，地震前出现的高梯度带与震中在空间上有一定联系，说明重力短波项高梯度带与地震前兆有关；③几次中强地震均发生在重力散度场的正源区内。重力散度正源区是介质密度减小的区域，其特征与地震前兆现象相吻合；④重力非潮汐变化的短波项图像的高梯度带和重力散度场图像的正源区虽然都与地震有一定的联系，但二者的物理意义不同，散度图像有比较明确的物理解释，并且避免了人为划分长、短波项的主观因素影响。
The long-wave and short-wave terms of the gravity change in Hexi-Qilian Mountains are separated by Fourier analysis, and then the formula of divergence field generated by gravity field is deduced. The gravity divergence values of each period are calculated, and the long-wave of gravity changes Term and shortwave term and divergence contour map. Based on the comprehensive analysis of the seismic activity in the area and the deep crustal structure data in the region, the following conclusions can be obtained: (1) The longwave term of gravity non-tidal changes is caused by the deep crustal material migration, NW-trending, and tectonic movement Which is usually related to the succession of the Earth’s crust. It is usually regarded as the normal value of the crustal movement. (2) The shortwave term of gravitational non-tidal changes is caused by shallow crustal factors. The image features are closely related to regional tectonic activities. There is a certain connection in space, indicating that the high gradient zone of gravity shortwave term is related to the earthquake precursors. (3) Several moderate earthquakes occurred in the positive source region of the gravity divergence field. The gravity source area is the area with reduced medium density and its characteristics are consistent with the seismic precursory phenomenon. (4) The positive gradient of the high-gradient zone and gravity-divergence field images of the short-term image with gravity and non-tidal changes are both related to the earthquake There is a certain relationship, but the two have different physical meanings, and the divergence image has a relatively clear physical explanation and avoids the subjective influence of artificially dividing long and short wave terms.