The invention discloses a terrace embedded type underground nuclear power station which comprises a nuclear island and a conventional island. A nuclear building of the nuclear island is arranged in a mountain nuclear island cavern group, the conventional island is arranged on a terrace platform on the upper portion of a mountain side slope, and the nuclear island cavern group is embedded in a mountain relative to the conventional island. The terrace embedded type underground nuclear power station is suitable for the terrain environment where no proper platform is formed on the outer side of the mountain side slope or a large terrace platform is formed on the upper portion of the side slope or a large platform is easily formed by manually excavating the upper portion of the side slope, and feasible general arrangement is provided for underground nuclear power station building. A main process system does not need to be greatly adjusted relative to a ground nuclear power station, and the technological development difficulty of the underground nuclear power station is lowered. Nuclear island plants are arranged in different underground caverns, and it can be guaranteed that an existing underground engineering technology meets the requirement that the nuclear building of the nuclear power station is arranged underground.