Abstract:In adaptive radar target detection, a common assumption is that the training samples and the clutter components within the cell under test follow an independent and identical distribution. However, in real-world applications, a multi-tude of nonhomogeneous factors can cause the contamination of some training samples by outliers. Consequently, devel-oping effective training sample selection techniques is crucial. First, these techniques are categorized into four main types based on existing literature: clutter power methods, knowledge-aided methods, feature similarity methods, and other selec-tion methods. Clutter power methods can be divided into power selection training, generalized inner product, and adaptive power residual. Knowledge-aided methods consist of two types: the first directly selects terrain data using information, while the second concentrates on reconstructing the test covariance matrix. Feature similarity methods focus on the dis-crepancies between the spectral and covariance matrices of training samples. Other methods emphasize the integration of various technologies with training sample selection, including sparse recovery, subaperture processing, and multi-frame techniques. In conclusion, the training sample selection methods are summarized and prospected, the potential challenges and issues faced by the screening methods in practical applications are given.