Recently, Hone, Novikov and Wang have given a list of generalized short pulse equations which are integrable. Among them, three are related to the 3-reductions of BKP/CKP hierarchies. In this talk, we will focus on two generalized short pulse equations which are not known until Hone et al.'s work. We will construct their integrable semi-discretizations based on their connections of 3-reduction of negative BKP/CKP hierarchies. This is a joint work with Dr. Na Xiong.