Abstract: The research compiles both the high energy and very high energy observed spectral index of 126 BL Lac objects and employs a math model (ΔΓ_obs=αz+β) to study the energy spectral break (the difference between very high energy and high energy observed spectral indices). Our goal is to determine whether the extraterrestrial galactic background (EBL) attenuation is an exclusive origin for the energy spectral break of the distant BL Lac objects. The results of statistical analysis show:α≠0 and β≠0. It also shows the energy spectral break contributes both to the EBL attenuation and some other physical processes.