This paper summarized the typical underground fluid anomalies and discussed the possible mechanism of the Anqing M_S4.8 earthquake and the Gaoyou-Baoying M_S4.9 earthquake. The results show that the characteristics of the underground fluid anomalies before the two earthquakes are very similar. According to the duration time,both of them include medium-term trend anomalies and short-term anomalies. There is also certain regularity on spatial distribution. During medium-term stage,the water level of outlying wells shows a downward trend,and the water level of wells close to epicenter shows a rising trend. The distribution orientation of the water level with the rising trend is the same as the trend of the earthquake fault. During short-term stage,anomalies migrate far from the epicenter in the short-term stage first and migrate back close to the epicenter in the impending-term stage. The regularity distribution of the water level probably is controlled by the regional stress field and structure patterns.