To enable image segmentation tasks to go beyond microcomputers and similar devices and better adapt to the limited computing and storage capabilities of mobile devices, we have proposed a lightweight semantic segmentation network called Mix-net. Firstly, we designed a Mix Convolution (MC) module for feature extraction and recovery, which significantly reduces the number of parameters in the model while maintaining accuracy. Secondly, to enhance the edge details of various semantics in the images, we simultaneously train two network models. One model focuses on learning the main body details of the images, while the other model is specifically designed for segmentation tasks and is more dedicated to capturing the edges of different semantics. Thirdly, we designed a novel activation function called Mix Rectified Function (MRF), which effectively enhances the accuracy of segmentation tasks and is more suitable for lightweight image segmentation tasks. Additionally, we have employed Group Normalization (GN) to complement MRF for normalization and activation operations, enabling higher accuracy for small-batch segmentation tasks. Finally, our proposed network retains skip-connection structures and incorporates channel shuffling and attention modules to enhance accuracy. We have conducted comparative experiments on the Cityscapes dataset, where Mix-net achieved an Mean Intersection over Union (MIoU) of 81.1% and a smaller model size, utilizing only 1.47M Parameters and 9.93G Floating Point Operations (FLOPs) on a single NVIDIA GeForce RTX3060 graphics card.