Communication method and apparatus based on QoS in network slice-based mobile communication network. The method includes determining whether first sum of bitrate of SDF requested from PDU and a using NSB of network slice corresponding to requested SDF exceeds reference NSB allocated to network slice, determining whether second sum of bitrate of requested SDF and a first using SB of APN corresponding to requested SDF exceeds first reference SB allocated to APN, unless the first sum exceeds the reference NSB, determining whether third sum of bitrate of requested SDF and a second using SB of PDU flow corresponding to requested SDF exceeds second reference SB allocated to PDU flow, unless the second sum exceeds the first reference SB, and processing the requested SDF to guarantee that quality of requested SDF is greater than or equal to a predetermined level, unless the third sum exceeds the second reference SB.