Infrared (IR) small target detection in complex background is one of the key techniques in many defense systems. In this paper, a novel method based on infrared patch-tensor model with structured sparse regularization (IPTSS) is proposed for small IR target detection. To overcome the structured edge interferences , the IPTSS model adds an edge structured sparse item utilizing the ℓ1,1,2 norm minimization constraint to the IPT model based on partial sum of tensor nuclear norm (PSTNN). An efficient optimization algorithm based on alternating direction method of multipliers (ADMM) is designed to solve the proposed IPTSS model. After the target-background-edge components are separated, the target image can be reconstructed. Finally, small targets can be extracted easily via adaptive threshold segmentation in the reconstructed target image. Extensive experimental results demonstrate that the proposed method can effectively enhance small IR targets while suppressing the complex background in various scenes.