Let \(S\) be a semitopological semigroup. The \(wap-\) compactification of semigroup S, is a compact semitopological semigroup with certain universal properties relative to the original semigroup, and the \(Lmc-\) compactification of semigroup \(S\) is a universal semigroup compactification of \(S\), which are denoted by \(S^{wap}\) and \(S^{Lmc}\) respectively. In this paper, an internal construction of the \(wap-\)compactification of a semitopological semigroup is constructed as a space of \(z-\)filters. Also we obtain the cardinality of \(S^{wap}\) and show that if \(S^{wap}\) is the one point compactification then \((S^{Lmc}-S)*S^{Lmc}\) is dense in \(S^{Lmc}-S\).