The effect of various replacement ratio of recycled sand on the early age behavior of 3D printing recycled mortar was studied. The effect of fibre content on the printing behavior was also explored by adding ultra-high molecular weight polyethylene fibers. The results show that the addition of recycled sand accelerates the early age strength development of 3D printing recycled mortar. The growth rates of green strength of 3D printing recycled mortar with 50% and 100% recycled sand are 3.2 times and 16.7 times of those specimens without recycled sand， respectively. The growth rate of early age strength of recycled mortar is not affected by the addition of appropriate amount of fibers， while the development of early age strength of recycled mortar is adversly affected by the addition of excessive fibers.