A liver CT image segmentation system and algorithm based on mixed supervised learning is provided. The image segmentation system includes an image preprocessing unit, a feature extraction unit, a word vector segmentation unit and a single-layer convolutional classification unit. The image preprocessing unit is in data connection with the feature extraction unit. The feature extraction unit is respectively in data connection with the word vector segmentation unit and the single-layer convolutional classification unit. In the present disclosure, a multi-task framework is used for respectively performing segmentation and classification tasks, to achieve high segmentation precision through a large number of weak label data and a small number of strong labels.