Waste paper fibers (WPFs) were incorporated into mortar to study the effect of the WPFs on mechanical property, the early age shrinkage and pore structure of the mortar. The use level of dry WPFs was fixed at 1% and 2% by mass of cement. In addition, the WPFs were mixed with cement using wet mixing and cured with sealed curing and standard curing. Results show that the WPFs do not improve the toughness of mortar with a sealed curing in a water cement ratio of 0.3, the cumulative pore volume and self shrinkage are increased instead. However, the WPFs can significantly improve the toughness of mortar in a water cement ratio of 0.4, and when the use level of WPFs is 1% by mass of cement, the ratio of flexural strength to compressive strength (σF/σC) is highest, cumulative pore volume is lowest and the anti shrinkage of mortar is enhanced. Moreover, compared with sealed curing, the WPFs do not improve the early age shrinkage of mortar with a standard curing, but reduce the long term volume expansion, and the restraint becomes better with the increase of the use level of WPFs.