To further explore the character of long-term change of haze over Shandong Province and provide theoretical basis for the government decision making and air quality forecasts, in this study by using the surface observation data (1961─2013) collected from 80 meteorological stations of Shandong Province, giving the definitions of seasonal change and inter-annual variability rates to measure the extent of the seasonal and inter-annual variations of haze, combined with several statistical methods such as polynomial and linear fitting, the seasonal characteristic of haze over Shandong Province in a recent 53 years were analyzed. The results indicate that the distinct seasonal characteristics of the occurrence of haze in the last century have become indistinct going in the 21th century, the frequent periods of haze days have been spreading from winter to autumn, summer and even spring. The seasonal change rate of haze days in 1960s was up to 84.0%, 1970s─1980s years ranged over 72.4%~73.6%, dropped to 56.4% in 1990s, while in recent 13 years of this century was as low as 42.3%, which indicated that the seasonal differences of haze days have steady declined. Haze pollution, previously happened in winter in Shandong Province, has tended to be a frequently occurring phenomenon in all over the year. The analysis on the inter-annual and spatial variations of haze over Shandong Province in different seasons also indicated that haze days averaged over Shandong Province exhibited an increasing trend during 1961─1990, and then grew slowly after 1990 with fluctuating at high pollution levels. The regions with high frequent haze are centered over Jinan, Jining-Taian-Laiwu area, Zaozhuang-Linyi area, Qingdao and the west area of Liaocheng city. The highest numbers of haze days in the 53-year average reached to 80.9, 78.2, 69.0 days per year for Jinan, Linyi, Qingdao respectively. In terms of the geographical distributions of inter-annual variability rate of haze, central-eastern Shandong experienced the higher inter-annual variation rates than western Shandong. The large inter-annual variations of haze days concentrated over the central and southern regions as well as the southern Shandong peninsula. Seasonally, the inter-annual increase rates peaked in summer with the values of higher than 4.5%·a~(-1), and then followed by autumn and spring, and dived in winter with the increase rate of lower than 1.5%·a~(-1). The indistinct seasonality of haze is exhibited in most areas of Shandong over the recent 53 years.