This article reviewed studies on the abnormal sex ratio at birth in China. The abnormality in the sex ratio at birth is a complicated result of China's social, economic and political context. It was a nationwide phenomenon in the 1980s and became more visible at present. The possible causes of the abnormal sex ratio at birth included not only the real imbalance due to the disturbance of social factors, but also a false one attributable to the undercounting of female births. Furthermore, traditional Chinese medicine practice in determining the sex of the fetus shows significant effect to abnormal sex ratio at birth. The high accuracy of traditional Chinese medicines in predicting the sex of the fetus can lead to sex-selective abortion and female infanticide which in a way leads to abnormal sex ratio at birth. The abnormality is also complicated by certain socioeconomic settings such as regional development and progress of fertility transition. However, irrespective of the causes of the situation, the root reason is the existing inequality between men and women.