With the development of network, IP geolocation technology has been widely used. Nearly all of the previous IP geolocation technology depends on the delay information. And most of them are based on the assumption of strong correlation between network delay and the geographic distance. But in China the correlation is weak. That makes the IP geolocation precision very low. To improve the problem, we geolocate by using the closest-shortest rule (with high probability the shortest delay comes from the closest distance) and association rules. We also design the landmark filtering algorithm and router repairing algorithm. What's more, we evaluate the geolocation precision of 996 landmarks, and make the error value within 4 km, greatly improving the geolocation accuracy.