The natural hydraulic lime and metakaolin as composite cementitious materials， polyvinyl alcohol （PVA） fibers， polyethylene （PE） fibers， or basalt （BF） fibers were incorporated to prepare the high ductility natural hydraulic lime based materials. The compressive and axial tensile properties， crack control abilities， and the reinforcing and toughening mechanisms of the fibers were experimentally investigated. The results show that the combination of PVA or PE fibers with quartz sand or limestone sand endows the natural hydraulic lime with excellent strain-hardening and saturated multiple-cracking characteristics， and significantly enhances the tensile strength and ultimate tensile strain of materials. The combination of PE fibers and limestone sand increases the ductility materials up to 5.604%， while the joint use of PVA fibers and quartz sand or limestone sand makes the ultimate tensile strain materials increased to more than 4.000%. Both PVA and PE fibers can control the crack width to below 100 μm， adding excellent crack control abilities as well as ultra-high deformation capacity of lime based materials.