The thinking of signal-to-leakage-plus-noise ratio (SLNR) is widely used for multi-user multiple-input multiple-output (MU-MIMO) systems in many works. We analyze the secrecy performance of the SLNR-based beamforming scheme in the multiple-input single-output multi-antenna eavesdropper (MISÓME) wiretap channel. Our analysis proofs the SLNR-based beamforming scheme has almost the same performance as the generalized eigenvalue decomposition (GED) based beamforming scheme, and has significant gain over the zero-forcing (ZF) beamforming scheme.