The aim of this study is to investigate the effect of different parameter of mix composition on fresh and rheological properties of printable mortar. Different binders were tested such as limestone filler (LS), and fly ash (FA). The water/binder ratio of 0.50 was used in this investigation. Superplasticiser (SP), viscosity modifying admixture (VMA) and sisal natural fibres (NF) were used in the investigation at different percentage. Furthermore, positive effect of fibres can be reversed when the dosage in fibres is too high (difficulties to extrude and drainage phenomenon which led to a stiffening of the mix). VMA caused an important loss of workability and time gap which influenced the passing ability of the mix through the extruder. Adding sisal fibres led to a greater yield stress, higher cohesiveness of the mix. Increase SP led to an increase in slump flow and penetration values and reduced the yield stress which can affect the stability of the shape of printed layers.