Addition of rice husk ash (RHA) is an effective internal curing method to mitigate self-desiccation and autogenous shrinkage of hydrating cementitious materials. Although a certain number of experimental research studies on this topic have been carried out, comprehensive investigation of the numerical simulation of the mitigating effect of RHA on autogenous shrinkage of cementitious materials is still scarce. In this study, a numerical model of autogenous shrinkage of RHA blended cement mortar was proposed. The proposed numerical model was based on a Pickett model and improved by taking the visco-elastic behaviour of RHA blended cementitious materials into account. Final setting time, chemically bound water, compressive strength, internal relative humidity (RH) and autogenous shrinkage of pure Portland cementitious materials and RHA blended cementitious materials were experimentally studied. The liquid absorption capacity and water vapour desorption isotherm of RHA were also measured. Comparison between the simulated and measured autogenous shrinkage showed that the autogenous shrinkage of RHA blended cement mortar can be predicted accurately with the proposed numerical model.