A method for performing pipeline-based accessing management in a storage server and associated apparatus are provided. The method includes: in response to a request of writing user data into the storage server, utilizing a host device within the storage server to write the user data into a storage device layer of the storage server and start processing an object write command corresponding to the request of writing the user data with a pipeline architecture of the storage server; utilizing the host device to select fixed size buffer pool from a plurality of fixed size buffer pools; utilizing the host device to allocate a buffer from the fixed size buffer pool to be a pipeline module of at least one pipeline within the pipeline architecture, for performing buffering for the at least one pipeline; and utilizing the host device to write metadata corresponding to the user data into the allocated buffer.