Based on the algorithm of singledifferencing for short baseline, this paper adopts the rate of phasedifferencing between two antennas as the indicator of cycleslip detection. We estimated the normal range of the rate and examined the effect of clock jump on it. Our theoretical analysis demonstrates that this indicator is able to detect cycleslip effectively. A numerical method for detecting and correcting cycleslip is provided. The experiments with real short baseline data from the clocksynchronized dualantenna receiver show that this method is valid in detecting and repairing the cycle slips, and it is immune to the disturbance of clock jumps.