Dual-injection in a spark-ignition engine has attracted extensive attention due to the advantage in controlling mixture formation and particulate emissions. The influence of direct-injection ratio (RDI) on combustion and emissions of a stoichiometric spark-ignition dual-injection gasoline engine at different throttle percentages (TP) and injection timings of direct-injection (DIIT) was investigated experimentally. Experimental results show that at a constant RDI (RDI > 0), the MCP (maximum cylinder pressure)TP=15%, DIIT=280°CA BTDC > MCPTP=15%, DIIT=50°CA BTDC≫MCPTP=7%, DIIT=280°CA BTDC > MCPTP=7%, DIIT=50°CA BTDC. The RDI has a significant effect on low and medium loads and DIIT = 50°CA BTDC. The maximum cylinder pressure, maximum heat release rate and maximum cylinder temperature fall significantly with increasing RDI, and their corresponding crank angles are delayed obviously with increasing RDI. The RDI has an obvious influence on combustion starting point, combustion center and combustion duration at low load and late DIIT. At RDI = 100%, the COVimep (coefficient of variation in indicated mean effective pressure) of TP = 7% and DIIT = 50°CA BTDC reaches the highest value of 13%. Except TP = 7% and DIIT = 50°CA BTDC, the COVimep of other case conditions can be controlled below 5%. At RDI = 50%, BSNOX(brake-specific nitrogen oxides)TP=15%, DIIT=280°CA BTDC emissions are approximately 23.3%, 128.4% and 214.1% higher than BSNOX TP=7%, DIIT=280°CA BTDC, BSNOX TP=15%, DIIT=50°CA BTDC and BSNOX TP=15%, DIIT=280°CA BTDC emissions, respectively. At RDI = 50%, the sootTP=15%, DIIT=50°CA BTDC emission is approximately 49.9% higher than sootTP=7%, DIIT=50°CA BTDC emission, sootTP=7%, DIIT=50°CA BTDC emission is approximately 28.6 times higher than sootTP=15%, DIIT=280°CA BTDC emission, and sootTP=15%, DIIT=280°CA BTDC emission is approximately 11.1% higher than sootTP=7%, DIIT=280°CA BTDC emission. Through comprehensive compromise of combustion and emission performance, the best RDI is 40%–60%.