The invention relates to a sensor installing base and a displacement measuring device using the sensor installing base. The sensor installing base comprises a pedestal used for being connected with the fixed part of a corresponding linear displacement sensor and also comprises an auxiliary slide block which is arranged at the rear end of the pedestal and used for being arranged between the moving part of the linear displacement sensor and a measured member in a transmission way. The pedestal is provided with a pedestal supporting surface which extends along a vertical direction. The auxiliary slide block is provided with a slide block supporting surface which is matched with the pedestal supporting surface in a supporting and sliding way. The pedestal supporting surface is a plane. The slide block supporting surface is an arc surface which extrudes towards the direction of the pedestal supporting surface with the axis extending along a left-and-right direction. The slide block supporting surface and the pedestal supporting surface are matched in a linear contact way. A problem of deformation of the pedestal caused by inclination of the auxiliary slide block in the prior art can be solved by the sensor installing base and the displacement measuring device using the sensor installing base.