The concepts of cultivated land ecounit and cultivated land niche are proposed based on niche theory.

The author firstly puts forward some concepts about cultivated land ecounit and cultivated land niche,and expounds its object,essence,types,chatacteristic and development law based on niche theory.

This paper proposes the concepts of cultivated land ecounit and cultivated land niche,then expounds its chatacter and development law based on niche theory.

This paper singles out the ecological footprint of cropland from 6 types of land use as study topic focusing on the regional differences in Jiangsu province,revises the ecological carrying capacity with productivity factor because land use efficiencies vary across regions,and uses ecological gap index(EGI) in place of ecological deficit or remainder to evaluate the ecological .

Cultivated land protection is the basis for realizing sustainable development strategy,ecological protection of cultivated land is an important components of cultivated land protection,it is also the premise of agricultural sustainable development.

According to the status quo of farmland utilization of Hubei Province from 1995 to 2004,this paper analyzes the major problems in terms of farmland ecological safety,and then puts forward countermeasures to guarantee farmland ecological safety,such as establishing a warning system,making some ecological payment,doing land arrangement,and so on.