Abstract: Based on the fiber circulating delay line, an optical pulse active replicator using semiconductor optical amplifier (SOA) was proposed for high-fidelity replication of short analog optical pulses according to the requirements of a short optical pulses measurement system. Taking into account amplified spontaneous emission (ASE), a numerical model of SOA was developed in order to investigate a single-shot optical pulse recirculating propagation in the active replicator with a SOA. Simulation and analyses indicate that the optical pulse active replicator, which uses pumping light injection to restrain pulseshape distortion, is feasible. The number results provided optimal design bases for the optical pulse active replicator by choosing appropriately operating parameters, such as the power of pumping light injection and the loss within the replicator loop.