Abstract: Distribution of Arps decline parameters and its effect factors of oilfields were summarized.In terms of analyses and research of references at home and abroad, a method for calculating Arps hyperbolic decline parameters has been screened, which is more reasonable, more simple and clear and much easier to use.By using this method, the data from 75 domestic waterflooding sandstone oilfields and 10 bottom water limestone oilfields, and 17 waterflooding sandstone oilfields in the Soviet Union have been handled, corresponding Q_i, n and Di have been calculated and the histograms about n and D_i distribution on oilfield's number have been made.The conclusions have been drawn from the histograms: ①waterflooding oilfields followed Arps decline, Oilfield's number of 0 <n <1 took 85%~ 90 %;②when n got larger gradually, ratio of oilfield's number changes from large to small;③ n >0.1 could appear for waterflooding oilfields at home and abroad, its oilfield's number took 10 %~ 15% in total;④ during oilfield development after presence of declinine, n is a variable;⑤D_i is mainly distributed in 0.1<D_i <0.3 sections for waterflooding sandstone oilfields and in D_i >0.4 sections for bottom water limestone oilfields.

Key words: Decline, Waterflooding, Oilfield, Parameter, Distribution