Abstract: Long-short axis is one of the most simple,prompt and operational methods among the limited deformation methods in outdoors. It requires studies as acircul arsection or circul arsection of strainellip soid and normal distribution before their deformations. But it is difficult to find the criterion particle in granite areas.In the 1:250000 regional geological mapping of Yumenzhen,the authors studied deformation feld spar by long-short axis measurement method,compared with the deformation gravel, deformation amygdale,deformation relict long-short axis measurement,then found the both mea surements were similar to deformation axis. It has been proved that deformation feld spar can be studied as to an area deformation cha racteristic of Yumenzhen1