Abstract: BPU-SPAR system is a stream AND parallel Prolog system which is implemented on SUN workstation, based on BPU-Prolog system. It inherits the structure-sharing mechanism of BPU-Prolog, and yet the execution speed is comparable with the PARLOG based on WAM. BPU-SPAR provides the framework in which a parallel CLP(Constraint Logic Programming) system is being developed. This paper presents the implementation and optimization techniques used in BPU-SPAR.