Abstract: This paper studys the size distribution of nature gas input among provinces from 2002 to 2012 based on Zipf law and difference degree model.The conclusion is:① Size distribution of nature gas input among provinces from 2002 to 2012 basically follow Zipf law,and the change of Zipf parameter is consistent with the change of difference degree.② Provinces in the non-scaling ranges is generally increasing,which shows size distribution of nature gas input among provinces in China is being gradually optimized.③Fractal evolution law of size distribution of input of nature gas among provinces is different each year.Except 2011,each year has two non-scaling ranges,complying with double fractal.2011 has a non-scaling range,complying with single fractal.④ In the first range of 2002~2005,the rank-size distribution of the nature gas input in this four years complies with lognormal distribution model; 2006~2008,Pareto model;2009~2012,lognormal distribution model.In the second range of each year except 2011,the rank-size distribution in those years complies with irregular Pareto model.⑤The change of size distribution of the nature gas input was relative to many factors,e.g.the production place,reserves and yield of large gas field,discovery of new gas field and decline of old gas field,level of economic development among different provinces and years.