Abstract: Ultra-precision displacement measurement technology, utilizing grating interferometers, is pivotal in the field of advanced manufacturing. Employing gratings with higher line densities is a proven method to enhance the accuracy and resolution of these interferometers. Advances in electron beam lithography for grating fabrication have enabled the use of high line density gratings (exceeding 3000 lines/mm) as measurement standards, significantly optimizing interferometer performance. This research employs a high line density electron beam direct-write grating with 3333 lines/mm in a single-path Littrow configuration. The interferometer, characterized by a base signal period of 300 nm, showcases its accuracy and stability in displacement measurement. The comparative setup between this single-path Littrow grating interferometer and a laser interferometer opens new avenues for grating pitch calibration. This study marks a valuable exploration in precision displacement measurement using electron beam direct-write high line density gratings.