Abstract: A method for reserving a cloud-based instrument and adapted to a system for reserving an instrument is provided. The system includes a group of remote instruments with a plurality of remote instruments, a system for reserving an instrument, and a bastion server. The reservation information includes a plurality of reservable time periods and a plurality of reserved time periods. The method for reserving the cloud-based instrument includes: establishing a secure connection between the bastion server and the remote instrument designated in any one of the reserved time periods, establishing a dedicated connection between the designated remote instrument and a user workstation designated in any one of the reserved time periods at start of any one of the reserved time periods according to pairing information and the reservation information, and terminating the secure connection and the dedicated connection at end of any one of the reserved time periods.