The challenge of detecting the dim small target in complex scene is to suppress the edge interference and the noise. A dim small target single-frame detection method based on structure tensor analysis is proposed. By adopting the structure tensor, which can measure the different local structure information, the structure tensor response map is calculated by employing the eigenvalue matrix of the structure tensor and the mean filter. A gray difference map is computed by adopting difference of Gaussians band-pass filter. By normalizing and fusing the two maps, the final response map is obtained. The target can be detected by segmenting the final response map with an adaptive threshold. Experiments with the standard infrared and visible datasets are performed including the different scenes such as sky, sea etc. Results demonstrate that the proposed algorithm can suppress background and nosie effectively, and detect targets efficiently and accurately in comparison with several typical methods.