The present invention provides a locking method and system, and the method includes: a locking system performing a phase discrimination and conversion process to an input signal Fi of an external standard source and a feedback output signal F0 of a local thermostatic crystal oscillator which pass through a frequency division, to generate a clock signal clk and a signal sign which is used to denote a frequency size relationship between the signal Fi and the signal F0, and performing a filtering process to the signal clk and the signal sign, and performing a voltage controlled oscillation process to a signal ahead used to denote that the frequency of the signal F0 is lower than the frequency of the signal Fi and a signal lag used to denote that the frequency of the signal F0 is higher than the frequency of the signal Fi, to implement a locking of the signal F0 and the signal Fi.