The article studied the effects of VGT opening on combustion characteristics and emission characteristics of a gasoline/diesel dual‐fuel engine, including in‐cylinder combustion pressure and temperature, heat release rate and combustion phasing, maximum pressure rise rate and combustion stability, and fuel consumption and emissions. The results showed that with the increasing of VGT opening, peak combustion pressure increased and its phasing was advanced; CA10, CA50, and left exothermic peak phasing were also advanced; peak average in‐cylinder temperature was reduced; peak pressure rise rate increased for SOI1‐15 strategy, while VGT opening had little influence on it for SOI1‐18 strategy but the most of their values were higher more than 0.75 MPa/°CA so that causing the engine to work roughly; the COVimep decreased, indicating the combustion tended to stability; brake‐specific fuel consumption decreased first and increased, and there was a minimum value at VGT60;both NO x and soot emissions were simultaneously reduced, while CO emission was increased and HC emissions had little changes. This research can be helpful to guide future works on dual fuel RCCI combustion strategies. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13059, 2019