As a prime coat material, emulsified asphalt has an effective consolidation effect on the semi-rigid base layer, biomass oil can effectively increase the penetration depth, but its content will also lead to the loss of bonding effect when it is too large, so the optimal biomass oil content needs to be further determined. In this paper, based on the theory of drying film formation of emulsified asphalt, molecular dynamics simulation and experimental methods such as viscosity test, contact angle test and maximum particle accumulation rate test were used to investigate the wetting performance indexes of emulsified asphalt particles with different biomass oil contents in the particle filling stage. Further the formation time of the maximum stacking rate of particles and the stabilization time of the relative concentration of emulsifiers in the drying film stage were also studied. The biomass oil emulsified asphalt has the best penetration performance when the ratio of biomass oil/asphalt is 1:3. In this dosage, emulsified asphalt can not only ensure that in the pre-construction can penetrate into the aggregate in a certain depth of penetration, to ensure that the construction effect of the early stage, and also in the later stage can reach a deeper depth of penetration, and thus better consolidation and strengthening of cement stabilized gravel base.