The device consists of: processor and its peripheral circuit; bus clock unit; and crystal oscillator. It also includes a clock alignment unit comprising of synchronous network interface unit, clock extract unit, clock processing and difference driving unit, clock difference receiving unit, digital PLL, crystal oscillator of PLL and hardware counter. The method includes: the device above is used toextract the clock source from synchronous digital switch network to take as benchmark of timing and to be in use for aligning the clock of software. By using the invention, the highly precise and highly stabilized clock source in data switch network can be used to make alignment.