Abstract: This paper presents a new method which uses the clock cursor feature between the sample clock and input signal and ADC quantization error suppression techniques under the background of the digital. On this basis, a precision frequency adjustment for crystal oscillator is designed for improving the long-term aging and the change of the frequency accuracy of traditional precision quartz crystal oscillator. Compared with most of the traditional frequency synthesizers generating certain step frequency signal in a large range, the main difference is that the device takes the non-standard frequency signal of crystal oscillator as a reference to realize standard frequency signal output through frequency adjustment function. Meanwhile, the output signal is obviously narrower in range, but of higher precision, which can realize the second stability of less than 3×10^-12 and a small frequency correction of 10^-11 orders of magnitude.