In this paper, configurations and performance of a pulse tube engine (PTE) are investigated. The configuration of PTE is basically designed by using a concept of energy flow. The configurations of PTE are classified as a PTE with two pistons and a PTE with one piston. First, the PTE with two pistons is simulated and the Carnot efficiency is about 41 %. The phase difference of between motion of two pistons located at expander and compressor mainly effects the performance of the PTE. Second, the PTE with one piston is designed. From a concept of analogy, the piston of compressor is replaced by a compliance tube and a resonator. The PTE with one piston is identical with a thermoacousic engine and has the large volume because the compliance tube and resonator are consisted of large volume tubes. Therefore, we will consider each usefulness of the compact PTE with two pistons and the huge PTE with one piston for PTE applications and the judgement of feasibility.