In this article, plane strain data were obtained from the line side strain recorded by extensometer installed in No.7 air defense cave of Huzhou Seismic Station, and the record of body drilling volume strain meter installed in the same cave, after eliminating gas pressure. Both synchronous data were compared and analyzed. Taking the strain solid tide of the Earth as the reference, it is found that the two types of data are basically the same strain and is proved that the surface strains observed by the two type equipments, with different length of the baseline and installation modes, are comparable in the band of solid tide.