LongVU is an innovative long video language understanding model that reduces the number of video annotations through a spatiotemporal adaptive compression mechanism while preserving visual details in lengthy videos. The importance of this technology lies in its ability to handle a large number of video frames while losing only a minimal amount of visual information within a limited context length, significantly enhancing long video content understanding and analysis capabilities. LongVU surpasses existing methods in various video understanding benchmark tests, particularly for tasks involving videos up to one hour long. Furthermore, LongVU can effectively scale down to smaller model sizes while maintaining state-of-the-art video understanding performance.