Based on the surface observational data of frost from 1957 to 2006 at 35 basic stations of Liaoning Province and the corresponding temperature data, the variation characteristics of frost and the effect of climate change on frost were analyzed. The result shows that the first frost delayed about 10 days in these 50 years, and the last frost brought forward 17 days, thus the frostless period extended 26 days. Besides, there was a break point in the 1990s for the first frost, last frost and frostless period. The areas in which the first frost significantly delayed, last frost significantly brought forward, and frostless period significantly extended, are mainly distributed in the middle part and the west part of Liaoning Province and the partial area of Liaodong Peninsula. The first frost date is more related to the temperature of September, the last frost date is markedly correlated with the temperature of April, while the frostless period is significantly correlated to the temperature from April to September. First frost delaying, last frost bringing forward and frostless period extending are all mainly attributed to temperature increases, especially the increases of the average minimum surface temperature and the average minimum air temperature. Due to temperature increasing, the spatial distributions of the first frost, last frost and frostless period all displayed the characteristics of moving from southwest to northeast.