Abstract: The coupling coefficient of yield-cultivated-land red-line analysis method based on reality and ideal grain yield helps to reveal the fundamental driving force and reasons for cultivated land red-line system development. This paper calculated the pothook rate of non-agricultural construction land index newly increased and efficiently using farmland abandoned by using the one-off coupling model and sustainable coupling model which efficiently used farmland abandoning permanently. Besides,a reliable frame of coupling red-line to upgrade from 2016 to 2033 was established. Finally,based on the cultivated land abandoned data of China,this paper investigated the changing tendency of coupling of yield red-line and cultivated land red-line in China by calculating the coupling coefficient and designing its upgrade steps. Results show that from 2001 to 2015,coupling of yield redline and cultivated land red-line in China was not ideal,especially after the secondary survey when the cultivated land was newly increased. On these grounds,suggestions are given as follows:(1)establish a cultivated land red line system of basic cultivated land red-line,legal cultivated land red-line,transition cultivated land red-line,the new pattern of cultivated land red-line and the ideal cultivated land red line;(2)establish a yield red-line system based on cultivated land red-line,consisting of basic yield red-line,legal yield red-line,transition yield red-line, the new pattern of yield red-line and the ideal yield red-line;(3)establish the coupling yield-cultivated-land red-line system consisting of basic coupling red-line,legal coupling red-line,transition coupling red-line,the new pattern of coupling red-line and the ideal coupling red-line. According to the average land abandoning rate of 11.12%,in the sustainable coupling mode,when per unit area new construction land index is increased,the government need permanently govern 28.85 times pastureland arable land. Compared with the base period,the government should upgrade the coupling of yield-cultivated-land red-line step by step to achieve the basic coupling red-line,the legal coupling red-line,the transition coupling red-line,the new pattern of coupling red-line,and the ideal coupling red-line in 2017,2021,2025,2029 and 2033,respectively,with the total grain yield increasing by 4.838 million tons,24.19 million tons,43.542 million tons,53.218 million tons and 88.246 million tons,and the red-line coupling coefficient increasing from 0.882 471 to 0.902 923,from 0.909 740 to 0.930 191,from 0.937 008 to 0.957 460,from 0.964 277 to 0.984 728,and to 1,respectively. Compared with that in 2015,the effective utilization of cultivated land area will increase by 12.5% and the total grain yield will increase by 14.2% in 2033. The innovation of this paper is to put up the system,methods,pattern and steps of coupling and upgrade the grain yield red-line and cultivated land red-line.

Key words: coupling, yield red-line, cultivated land red-line, urbanization, food security