Abstract: In astronomical observation, the long-slit spectrometer is a kind of spectral observation equipment commonly used. The long-slit spectral mode of the Beijing Faint Object Spectrograph and Camera (BFOSC) mounted on the 2.16 m telescope of the Xinglong Observatory, National Astronomical Observatories, Chinese Academy of Sciences, is widely used, but it is not equipped with a specific data processing software. After observation, users usually run IRAF software interactively to obtain the final data product. This paper introduces an automatic data processing software for BFOSC long slit spectrum. It includes bias and flat-field correction, background subtraction, spectrum extraction and wavelength calibration. We describe the processing method and the flow of the program, and present the results of processing with the observed data, and compare them with the IRAF results. Our software realizes automatic operation on the basis of completing all the necessary steps of spectrum processing, and adopts the optimal extraction method, which automatically deducts most cosmic rays and ensures the high precision of output results.