Text filtering is the procedure of retrieving documents relevant to the requirements of specific users from a large-scale text data stream. First, the TREC (text retrieval conference) as well as its text filtering track are introduced, which is the most authoritative international evaluation conference on text retrieval, from the aspects of tasks, topics, corpus and evaluation metrics. Then a text filtering system based on vector space model is presented. This system is composed of two phases of training and adaptive filtering. During the training phase, feature selection and pseudo feedback are used to select the initial filtering profiles and thresholds. During the filtering phase, user feedback is utilized to modify the profiles and thresholds adaptively. This system took participate in the 9th Text Retrieval Conference in 2000, and ranked high among all the 15 systems from many countries. Good performance has been achieved, where the average precisions of adaptive and batch filtering are 26.5% and 31.7% respectively.