Abstract: Based on the related typhoon data from 1949 to 1987, a study on the relative motion law of typhoon to its associated low in Taiwan Island and Taiwan Strait is presented.Tyhoon and its associated low revolve around each other. The probabilities of cyclonic and anticyclonic revolutions are almost the same, about 50 percent. The revolving direction may be determined qualitatively according to their azimuth. Cyclonic revolving angle is well related to their initial distance, intensity and azimuth.In regard to the effect of their interaction on typhoon (or low) track, about 1/3 of the cases show no clear change and the remaining 2/3 show a sunden change of track such as turning right and speeding up, turning left and slowing down as well as typhoon being substituted by developed low pressure. Some conclusions drawn from the analysis may be used for reference for weather prediction.