We consider the approximation of elliptic eigenvalue problem with an immersed interface. In this talk, the stability and convergence of an immersed finite element method (IFEM) for eigenvalues is proved by using Crouzeix-Raviart P1-nonconforming approximation. We show that spectral analysis for the classical eigenvalue problem can be easily applied to our model problem. We analyze the IFEM for elliptic eigenvalue problem with an immersed interface and derive the optimal convergence of eigenvalues. Numerical experiments demonstrate our theoretical results.