The Z Transform is a mathematical operation in signal processing, which gives a tractable way to solve linear, constant-coefficient difference equations. Based on the classical Z transform and inspired by the thought of sliding DFT, a new definition of Sliding Z Transform(SZT) is introduced and deduced. Then this method is applied to blind source separation, four simulation results are presented to demonstrate its performance when the sliding window WIN is set. It can directly recover time-domain sources from the convolutive mixtures with the help of robust linear mixed blind separation algorithms(such as JADE) . It has simple principle and good transplantation capability and can be widely applied in various fields of digital signal processing.