  The formation of quark-gluon plasma (QGP) in relativistic heavy ion
collision, is expected to be accompanied by a background of ordinary collision
events without phase transition. In this short note an algorithm is proposed to
select the QGP candidate events from the whole event sample. This algorithm is
based on a simple geometrical consideration together with some ordinary QGP
signal, e.g. the increasing of $K/\pi$ ratio. The efficiency of this algorithm
in raising the 'signal/noise ratio' of QGP events in the selected sub-sample is
shown explicitly by using Monte-Carlo simulation.
