A built-in-self-testing (BIST) circuit with digital output for phase locked loops-jitter testing and the method thereof are used to solve the problems of difficult processing and test of high frequency signals encountered during test of jitter signal of phase locked loops. The built-in-self-testing (BIST) circuit with digital output for phase locked loops-jitter testing comprises a phase locked loop unit electrically connected with a frequency divide unit. The frequency divide unit is electrically connected with a signal conversion unit. A digital computation unit is electrically connected with the signal conversion unit. A maximum hold circuit is electrically connected with the digital computation unit. After an input signal is provided to and processed by the phase locked loop unit, the maximum hold circuit outputs a self test output signal exhibiting the occurrence situation of jitter signal of the phase locked loop unit.