It is known that critical path test generation method is not a complete algorithm for combinational circuitswith reconvergent-fanout.In order to make it a complete algorithm,we put forward a reconvergent-fanout-oriented technique,the principal critical path algorithm,propagating the critical value back to primary inputsalong a single path,the principal critical path,and allowing multiple path sensitization if needed.Relationshipamong test patterns is also discussed to accelerate test generation. It is known that critical path test generation method is not a complete algorithm for combinational circuits with reconvergent-fanout. Order to make it a complete algorithm, we put forward a reconvergent-fanout-oriented technique, the principal critical path algorithm, propagating the critical value back to primary inputsalong a single path, the principal critical path, and allowing multiple path sensitization if needed. Relationshipsamong test patterns is also discussed to accelerate test generation.