In this letter, we consider the issue of detecting signal of interest under interference. Two multi-antenna based spectrum sensing algorithms are presented given the knowledge of interference's statistical characteristics. The first method is designed to neutralize the impacts of interference so that the generalized likelihood ratio test (GLRT) based method for interference-free environment can be used. In the second method, an optimization problem is formulated based on the GLRT concept and an approximate solution is derived in closed-form under low signal-to-interference ratio (SIR) condition. Numerical results are provided, which demonstrate the superiority of the proposed schemes compared with existing methods.