This study aims to investigate whether the gradient effect of OCP (the Obligatory Contour Principle) can mirror the co-occurrence restrictions across a syllable boundary in English phonotactics. For this purpose, this study collected the data from the Carnegie Mellon University Pronouncing Dictionary and employed the Observed over Expected (O/E) analysis which is introduced by Pierrehumbert (1993) to measure the OCP effects. As a result, our finding is that the co-occurrence of the two consonants sharing the same manner feature across a syllable boundary is strongly restricted by OCP. In terms of OCP-place, the effect plays a role in an opposite way in that the co-occurrence of two consonants sharing the same place features are more likely to be represented than other combinations. In conclusion, the heterosyllabic clusters represents an asymmetric tendency with regard to place and manner features in English phonotactics: they tend to be similar violating OCP in terms of the place of articulation, but they tend to be different satisfying OCP in terms of the manner of articulation. We can also capture the effects are applied in gradient fashion. Additional finding of this study is that the OCP-voice and the Syllable Contact Law (Vennemann 1988) effects are not active in heterosyllabic clusters of English words.