Abstract:The earthquake recording ability of borehole strain meter is researched and calculation steps and processing methods are discussed by taking the data of Changping TJtype borehole strain meters as an example. 20 TJtype borehole strain meters that have been installed in mainland China for longer time and with better data archived are selected as the study objects,their earthquake recording ability lines are calculated and show their earthquake response range for event of Ms6.0. This formula not only can quantify a strain meter’s earthquake response ability in location range and magnitude, but also is a new scientific method for assess a seismic instrument. At the same time,on the basis of common understanding that the energy released in the precusory period is supposed to be less than that released by the actual earthquake,this formula is also useful for determining precursor’s location and magnitude range.