The invention provides a log management system and a log collection method. The log management system comprises a plurality of data sources, a database server, and a log collection device. The plurality of data sources are used for generating logs of different formats; the database server comprises a modeless database used for storing the logs of different formats; and the log collection device comprises a log interface module used for providing log interfaces for the plurality of data sources so as to allow the data sources to send the logs of different formats to the log collection device through the log interfaces, and a log persistent module used for sending the logs of different formats to the database server so as to allow the database server to store the logs of different formats in the modeless database. The technical scheme of the invention does not need to uniform log formats, and mitigates the workload of application system access reconstruction.