前驱波是一种暂态信号，是在震源成核过程中发射出的一种低频波，对地震预测而言是一种有重要价值的可靠短临前兆信息。本文提取了黑龙江及邻区3 次中强地震前5 例水位、竖直摆倾斜数字化低频前驱波异常图像，分析了低频前驱波异常形态、异常特征和异常指标，经初步统计得到了经验公式，探讨了前驱波异常机理，取得了一些新的认识，值得一提的是这些震例均为近场区中强地震前数字化前兆低频前驱波异常，丰富了低频前驱波方法在黑龙江地区地震分析预测工作中的应用。

The precursory wave is a kind of transient signals and low-frequency waves in the process of source nucleation． It is also an important prediction value and reliable short-impending precursory information． This paper extracted 5 cases of digital low-frequency precursory wave abnormal images before 3 moderately strong earthquakes in the Heilongjiang and its adjacent area， and analyzed abnormal morphology，abnormal characteristics and abnormal index of low-frequency precursory waves． We got a new understanding on the basis of preliminary statistic analysis and precursory wave abnormal mechanization research． These earthquake cases have greatly enriched the digital low-frequency precursory wave before moderately strong earthquakes in near field region，and contribute to the application of low-frequency precursory wave on analysis and prediction work in the Heilongjiang region．

中国地震局地震科技星火计划项目(XH12015Y)、黑龙江省自然科学基金项目(200906)联合资助