The spreading behavior of a 3D droplet impacting on inclined solid wall is presented by using a lattice Boltzmann method (LBM) with single component multiphase pseudopotential model. The time evolution of spreading factor, dimensionless spreading width, dimensionless height, dimensionless bottom area and adhesion force are obtained. Our numerical results show that when increasing the contact angle or inclination angle, the dimensionless height and the dimensionless bottom area increases but the dimensionless spreading length and spreading width decreases. In addition, the progresses of circumferential spreading in starting-up and spreading stages and the aggregation at front edge in retracting stage would be more obvious by decreasing the viscosity or increasing the Bond number.