The cultivated land of Tibet Autonomous Region is distributed mainly in the river valleys of the east and south Tibet. Most of the cultivated fields were scattered in broken pieces

which

varying in their different pattens

mix up a large quantity of non-cultivated components. And therefore

it is difficult to measure the accurate areas under cultivation even with larrge scaled data. In order to make thorough investigation

the systematic methods were adopted creatively which includes （1） taking sampling strip aerial photographs; （2） calculating the value of non-cultivation coefficients of sample fields in the infrared colour air-photos by digital image processing system; and （3） Setting up the non-cultivation coefficient indexing table in different geomorphologic conditions and types of cultivated lands

etc. The methods that have been spreaded in the investigation of whole Tibet

have improved the investigation accuracy

shortened the time and redused the expens of manpower and funds. The study also provided efficent methods to investigate the cultivated areas in other mountainous regions in China.