In this paper, the authors deal with the testable design of conservative logic based sequential circuits by using two test vectors. The conservative logic based sequential circuits are built from the reversible gates. This reversible or information lossless circuits have extensive applications in quantum computing, optical computing, as well as ultra-low power VLSI circuits. The optimized designs of reversible D latch, reversible negative enable D latch, master slave flip-flop, double edge triggered flip-flops and its application circuits like reversible universal shift registers, four bit binary counter are proposed.