The paper presents a new approach for measuring the line-width enhancement factor (LEF) of semiconductor lasers (SLs). LEF can be measured using a technique called optical feedback self-mixing interferometry (OFSMI). However, the existing OFSMI based approaches require that optical feedback factor (denoted as C) associated with the SL systems within a narrow range. The proposed new method is also based on OFSMI principle. The method does not rely on the C factor, and is suitable for the whole moderate optical feedback regime. The associated simulations and the experiments are carried out for verifying the proposed method.