Gasoline direct injection (GDI) engine is now widely used due to its high fuel efficiency and low HC emission during cold start. However, high particle emission has become an inevitable challenge especially with injector deposits. In this paper, a 4-cylinder turbocharged GDI engine in Chinese market was selected and operated at 2000rpm and 3bar BMEP condition for 50 hours to accumulate injector deposits. The engine ignition angle, cylinder pressure, combustion duration, brake specific fuel consumption (BSFC), gas emissions ( THC, NOx, CO) and particle emission were measured before and after the injector fouling test at eight different operation conditions. The test results indicated that, although the injector flow rate and injection pulse did not change a lot after the injector fouling test which means few internal deposit was built inside the injector hole, it still had some effect on engine combustion and emissions. It was found that the combustion duration increased with the decrease of combustion efficiency and higher BSFC. More pre-ignition events may happen after the fouling test especially at high engine load which retard the engine ignition angle. Fouled injector had a higher NOx emission and lower THC emission. Particle number (PN) emissions at high engine load showed a dramatic increment after the accumulation of the injector deposits while decreased at low engine load.