The hydraulic power take-off(PTO) unit of the two-raft-type wave energy converter(WEC) is analyzed. A combined hydrodynamic and hydraulic PTO unit model of the two-raft-type WEC is proposed. The performance of the two-raft-type WEC is investigated and optimized. The relationship between the optimal power capture ability of the two-raft-type WEC and wave states is revealed. The difference in the performance of the two-raft-type WEC with two types of PTO units is revealed.