In this paper, a design principle and implementing method are given to get a kind of digital multi-function card, which load-bearing a signal source and digital cymometer with high precision. According to the adaptive control principle, the output of OCOX and PPS controlled by the circuits are built in CPLD. It can overcome the error brought by the interference pulse and the frequency drift caused by the OCOX and get sync source with high precision and precise frequency, which can been used in the frequency measurement circuit as the reference signal. By using it, the card can keep high precision for a long time and improve the performance and reliability.