To study the influence of the vapor-liquid two-phase concentrations of n-decane sprays under the same particle size condition on explosion parameters, the n-decane sprays with different concentration of vapor-liquid two-phase based on Sauter mean diameter D₃₂ were studied by an optical measurement system of particle size and concentration of liquid spray and a 20 L double pulse pneumatic spray multiphase explosion test system. The explosion parameters were measured. Results show that under the conditions of D₃₂ as 38.11 μm and ignition energy as 40.32 J, the low flammability limit(LFL) total concentration of vapor-liquid two-phase n-decane sprays is 199.29 g·m^-3, corresponding liquid-phase mass concentration is 151.34 g·m^-3 and vapor-phase volume concentration is 0.77%(V/V). The maximum detonation temperature peak and maximum detonation pressure peak in the flammable range of concentration is 812 ℃ and 0.97 MPa respectively. Under the condition of D₃₂ as 38.11 μm, the influence of liquid-phase concentration of n-decane sprays on the LFL is smaller, whereas the dominant factor affecting the LFL of n-decane sprays is vapor-phase concentration.