Terahertz imaging was new trend of space optical remote sensing imaging field. However, the resolution of terahertz imaging was difficultly raised, restricted by current level processing and manufacturing technology. The improvement method for terahertz imaging quality was presented to raise the quality of terahertz image. Firstly, the multi-observation stagger terahertz images were received, the target spectrum response ranges was terahertz. Then, the multi-observation images were norm optimization constrained and filtering enhanced. Finally, the higher resolution of terahertz image was reconstructed by multi-observation low resolution original terahertz images. The experimental result showed that target edge was more continuous after being processed by the proposed method. Besides, the background noise on original low resolution Terahertz image was constrained. The evaluation index of image quality was increased, which meant that the proposed method is better than conventional methods. The detail information of processed image was enhanced and then quality of the original terahertz image was improved.