Generating discernibility matrix consumes huge time and space .To solve this problem, A new Binary Discernibility Matrix (BDM) induced from information table is defined, The concept of Binary Conjunction Matrix(BCM) is then introduced, Finally A novel method for discernibility matrix using Ordered binary decision diagrams(OBDD) is proposed in this paper, experiment is carried to compare the storage space of discernibility matrix with that of OBDD, results show that the new method has better storage performance and improve the attribute reduction for those information systems with more objects and features.