In recent years, haze has become a serious problem in Chengdu area. Using surface observation data in Chengdu from 1980 to 2010 with two thresholds of relative humidity, this paper analysis the seasonal and inter-annual change of precipitation, relative humidity and average wind speed, and find the relationship between those meteorological elements with haze at the same time. The result shows the significant seasonal difference of haze when using two thresholds, it means the average number of haze days in winter is maximum among four seasons, while the haze days in summer is minimum. However, there is a significant difference between the two method when it comes to annual trend. Generally, the number of the haze days by using the old method shows a sharply increasing trend during recent years while the new one shows a weakly decreasing trend at the same time. It means the haze whose humidity is between 80% and 90% has been decreasing in recent year, and it may be related to the dry trend of atmospheric in Chengdu. The annual precipitation of Chengdu area shows a weak decreasing trend. When it comes to the relationship between haze and precipitation, using two threshold to calculate the correlation coefficient between precipitation and haze days in winter, the correlation coefficient are -0.559 and -0.534, respectively, and the remaining three seasons' precipitation is inversely related to the number of haze days, and their correlation coefficient are small. The relative humidity dropped to 80% since 1997, and the atmosphere shows dry trend. And two methods show the different relationship between the haze and relative humidity, the old one shows negative correlation and the correlation coefficient is -0.698, while the new one shows positive correlation. The frequency of calm in Chengdu area is high. The wind speed decreased significantly since 2005, and it is inversely related with haze days. In a word, the key point to the increased haze days is the dry trend of climate and the reduced wind speed.