利用Ｗｉｇｎｅｒ－Ｗｅｉｓｓｋｏｐｆ近似研究了光致离化系统中的暗态效应。在双模量子化光场的驱动下，三个束缚态形成一个暗态。即使在ｔ→∞的条件下，原子在该暗态上也能保持一定的占居数。还给出了光子数对原子在束缚态上的占居数的影响。 The dark state effect in photoionization system was studied by Wigner-Weisskopf approximation. Driven by the two-mode quantum light field, the three bound states form a dark state. Even in t → ∞ conditions, the atoms in the dark state can maintain a certain number of occupancy. The effect of photon number on the atomic occupancy of the bound state is also given.