Embodiments of the present disclosure provide an operating system startup method, apparatus and electronic device. A specific implementation of the method comprises: determining at least one target mirror server from a mirror server cluster based on a LinuxBoot on a diskless server, wherein a mirror file stored in a mirror server comprises a system kernel and a file system; downloading mirror file fragments from a target mirror server of the at least one target mirror server based on the LinuxBoot; assembling a plurality of downloaded mirror file fragments into a target mirror file; and booting an operating system of the diskless server based on a target system kernel and a target file system comprised in the target mirror file. Therefore, the efficiency and success rate of diskless boot-up of an operating system of the diskless server can be improved when booting the operating system based on the LinuxBoot.