Abstract: In order to study the energy dissipation characteristics of open ditch combined with the side ports located in an in-chamber culvert designed for a large-scale lock chamber with an extreme high water head, in case of the water head 60 m and the useful dimension of the lock chamber 280 m×40 m (length×width), the three-dimensional turbulent numerical simulation method was used to analyze the parameters such as velocity, turbulent energy distribution, remaining specific energy and flow velocity distribution uniformity, and present the energy dissipation characteristics of the single open ditch with double-layer side ports and the double open ditches with single-layer side ports. Moreover, the corresponding energy dissipation results between them were compared. The results show that for the case of the single open ditch with the double-layer side ports, when the ratio of vertical spacing d between ports to square root of side ports area D, d/D, increases from 2.29 to 5.71, the energy dissipation results become better firstly and then worse. When d/D reaches 3.43, the corresponding energy dissipation results become the best. In addition, the widening type of the double open ditches (the ratio of one open ditch width b to square root of side ports area D, b/D=2.71) has better energy dissipation effect than that of the type of the single open ditch with the double-layer side ports. The research results can provide a technical support for the design of energy dissipators in similar ship locks.