Based on daily data at 17 meteorological stations in Shandong Province during 1961-2012, the FAO Penman-Monteith formula and crop coefficient calculation were used to estimate water requirements of cotton during all growth stages. Combined with precipitation data, coupling between rainfall and crop water requirements of cotton were determined. The spatial distribution of mean coupling degree of the entire cotton growth period and each growth stage were derived with inverse distance weighted interpolation. The temporal trend of coupling was detected via linear regression. The results show that the mean coupling degree of the cotton growth period during the past 52 years ranged from 0.692 to 0.847. The spatial distribution of this degree was low in the west and north of Shandong province, but high in the east and south, with an increase from northwest to southeast. Guaranteed rates under 0.6 and 0.8 of coupling degree were low in the north and northwest of the province, such as in Dongying, Huimin and Dezhou, where total planted cotton area reached about 51% of total cotton area in the province in 2012. During the past 52 years, most stations in the province had decreasing trends of coupling degree for the stages of planting, first flower and open boll to harvest, as well as for the entire growth period. However, only 6 and 5 stations showed decreasing trends for the stages of seedling and first square, respectively.