Abstract��Since the common continuous data protection system just backups the modified data directly and consumes a large amount of storage space, this paper presented a continuous data protection system based on Timely Recovery to Any Point-in-time 4 (TRAP-4). This system captured the modified data from the user by volume filter driver, and the data would be backed up to the backup center after calculation and compression. The recovery process can recover the data volume to any time-point through reverse decompressing and reorganizing the compressed data. Experiment shows this system can effectively save the storage space compared to common method. And, as the block size increases and decreases to modify the file, the system further reduces the storage space usage.