The warship, which the navy says is harder to detect on radar, is expected to emerge after China puts into service its first battle carrier group, the legislator said.
The twin-hulled boat will be armed with up to eight home-grown Hsiung-feng II ship-to-ship missiles and eight other more lethal Hsiung-feng III anti-ship supersonic missiles.
The remarks came as China has been restoring Varyag, a former Soviet aircraft carrier bought in 1998.
The aircraft carrier will be used for training and as a model for a future indigenously-built ship, according to Andrei Chang, head of the Kanwa Information Centre, which monitors China's military.
The ship, currently based in the northeast port of Dalian, could make its first sea trip "very soon," he said.
Calls have been mounting on the island for the military to come up with counter-measures against the perceived threat.
Ties between Taiwan and China have eased markedly since Ma Ying-jeou of the China-friendly Kuomintang party came to power in 2008, ramping up trade and allowing in more Chinese tourists.
But Beijing still refuses to renounce the use of force, even though Taiwan has been self-governing since 1949 at the end of a civil war, prompting the island to keep modernizing its forces.