For diesel/natural gas dual fuel engine, the combustion of pilot diesel plays an important role to the following mixture combustion process. To better understand the effects of multiple injections, a detailed study was conducted on a 6-cylinder turbocharged intercooler diesel/natural gas dual fuel heavy-duty engine at low to mid-range loads. Multiple variables were tested, including single injection timings, multiple injections timings and mass ratios, natural gas percentage of energy substitution, engine speeds and loads. The investigated results show that pilot diesel multiple injections have an obviously effect on not only pilot diesel combustion process but also natural gas mixture combustion process. Early injection leads to pilot diesel ignition mode differs from traditional diesel engine compression ignition mode in the sense that it does not occur at a specific place in the spray, which is a two-stage auto ignition mode. Engine combustion and emissions characteristics, including cylinder pressure, cylinder temperature, heat release rate, start of combustion (SOC), ignition delay, combustion duration, crank angle of 50% heat release (CA50), nitrogen oxides (NOx) and total hydrocarbon (THC), show completely different variation trends in multiple injections conditions. Overall, higher thermal efficiency and lower emissions can be achieved with multiple injections when compared to conventional single injection.