Increasingly, oil spills and industrial discharges are wreaking havoc on the water environment; in order to efficiently separate oil and water from sewage containing oil or organic solvents, a novel porous polymer (P(EHA-co-BA)) was prepared by Pickering high internal phase emulsion (HIPE) template method. To obtain polyHIPE with better oil/water separation capacities, octadecyltrichlorosilane (OTS)-modified carbon nanotubes (CNTs) and surfactants were used as costabilizers for HIPE, which improved the stability of HIPE as well as the mechanical properties and the separation efficiency of polyHIPE. In the presence of 1 wt % OTS-CNT adding in the oil phase, 1%OTS-CNT polyHIPE has high porosity (92.21%), favorable hydrophobicity (a water contact angle of 128°), and excellent mechanical properties. As a result, 1%OTS-CNT polyHIPE has high absorption of oils and oily solvents, e.g., dichloromethane up to 36 g/g, and maintains an absorption efficiency of >97% after 20 reapplications. In the formulation of polyHIPE, cinnamaldehyde (CA) has been added to provide superior antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). It appears that the novel polyHIPE proposed in this work is a reusable antibacterial porous polymer with promising applications for oil-water separation.