Abstract: A clock and data recovery device and a jitter tolerance enhancement method thereof are provided. The clock and data recovery device includes a clock and data recovery circuit and a jitter tolerance enhancement circuit. A data input terminal of the clock and data recovery circuit is suitable for receiving a data signal. The clock and data recovery circuit recovers the data signal to a clock. The jitter tolerance enhancement circuit is coupled to the data input terminal of the clock and data recovery circuit to receive the data signal. The jitter tolerance enhancement circuit detects a correlation between the data signal and the clock and correspondingly adjusts a loop gain of the clock and data recovery circuit according to the correlation.