The laminar flame characteristics of ethanol/isooctane mixture with 10% ethanol volume fraction(E10) were investigated by using a constant volume combustion bomb system and high-speed schlieren visualization technology at different water vapor concentrations(0～10%) and initial temperatures(400～500K). The experimental results show that the laminar flame speed of E10/air decreases linearly with the increase of water vapor dilution ratio

and it increases exponentially with the increase of initial temperature. The dimensionless laminar flame speed decreases as the water vapor dilution ratio increases

and the effect of equivalence ratio is not significant. The sensitivity analysis shows that the chain branch reactions are beneficial to increase the laminar flame speed of E10/air

but the chain terminal reactions reduce the laminar flame speed. The dilution effect

thermal effect

direct reaction effect and three body effect of water vapor all will reduce the laminar flame speed of E10/air

and the dilution effect plays a leading role.