Yunnan is the most typical mountainous province in the west China，plains（flatland region）accounted for only 6.40% of the total land area. Currently，changing the unreasonable construction land expansion mode，reducing constructions on the flatland area with high quality cultivated land and promoting reasonable construction layout to the suitable ramp become an extremely important development strategy in Yunnan Province. Based on the current implementation situation of the strategy of “building urban and industrial projects on mountainland” established in 2011，this paper has explored and put forward four basic countermeasures to protect farmland in flatland area of Yunnan，namely：① to seriously implement the strategy of “building urban and industrial projects on mountainland”，feasibly setting up the concept of protecting cultivated land in flatland area；②to compile scientifically and implement strictly kinds of general land use planning which protecting cultivated land in flatland area，normalizing and regulating different departments user’s behavior of cultivated land utilization and protection in flatland area；③to delimit permanent basic farmland conservation area in flatland area，ensuring that more than 80% of the cultivated land in flatland area be permanently protected；④to strengthen the construction dynamics to well-facilitied capital farmland，further improving agricultural comprehensive productivity of the cultivated land resources in flatland area. This study means much significance as to further deepen the understanding of protecting cultivated land in flatland area and constructing mountain cities，scientifically promoting the strategy implementation of protecting cultivated land in flatland area and “building urban and industrial projects on mountainland”.