Title: A MULTI-SCALE STRUCTURE-PRESERVING HETEROLOGOUS IMAGE TRANSFORMATION ALGORITHM BASED ON CONDITIONAL ADVERSARIAL NETWORK LEARNING. Abstract: Image transformation model learning is a basic technology for image enhancement, image super-resolution, image generation, multimodal image fusion, etc. which uses deep convolutional networks as a representation model for arbitrary functions, and uses fitting optimization with paired image training sets to solve the transformation model between images in the different sets. Affected by the complex and diverse changes of the 3D shape of the actual scene and the pixel-level optical properties of materials, the solution of the heterologous image conversion model is an ill-posed problem. In recent years, most of the proposed conditional adversarial learning methods for image transformation networks only consider the overall consistency loss constraint of the image, and the generated images often contain some pseudo-features or local structural deformations. In order to solve this problem, using the idea of multi-scale image coding and perception, this paper proposes a multi-scale structure-preserving heterologous image transformation method based on conditional adversarial network learning. First, using the idea of multi-scale coding and reconstruction, a multi-scale, step by step generator lightweight network structure is designed. Then, two image multi-scale structure loss functions are proposed, and combined with the existing overall consistency loss, a loss function for generative adversarial learning is designed. Finally, test experiments are performed on the KAIST-MPD-set1 dataset. The experimental results show that, compared with the state-of-the-art algorithms, the proposed algorithm can better suppress the local structural distortion, and has significant advantages in evaluation indicators such as RMSE, LPIPS, PSNR, and SSIM.