The effects of sparking timing on combustion process and particle emission were investigated experimentally on a gasoline direct injection engine by using combustion analyzer and DMS500 fast particulate spectrometer. Results showed that with the delay of spark timing, flame development duration decreased gradually, and rapid burning duration increased gradually. Peak value of heat release rate and cylinder mean temperature showed a gradually decrease and backward shift, which induced a slow heat release process and high cylinder temperature in expansion stroke. Also, spark timing delay led to decrease in the peak cylinder pressure. Moreover, exhaust particles from GDI engine exhibited a bimodal size distribution including nucleation mode and accumulation mode particles. As the reduce of spark advance, total particle number concentration and peak value of particle number density in nucleation mode and accumulation mode decreased gradually, and peak size of accumulation mode particles showed a decreasing trend, but spark timing exhibited a slight influence on peak size of nucleation mode particles.