The invention discloses a saggar for a roller kiln for soft ferromagnet production and a preparation method of the saggar. The saggar is prepared from, by weight, 30-50 parts of sintered mullite, 10-20 parts of andalusite, 0.1-1 part of zirconium oxide fibers, 1-5 parts of kaolin, 15-25 parts of low-sodium aluminum oxide, 5-10 parts of activated aluminum oxide, 10-20 parts of aluminum-rich spinel,0.2-0.6 part of dextrin and 0.2-0.8 part of calcium lignosulfonate. The saggar is high in thermal shock resistance stability and high in refractoriness under load, the surface SiO2 content of the saggar can be reduced, and reaction between the saggar and soft ferromagnet is reduced; according to utilization in a soft ferromagnet calcining kiln, no adverse reaction is caused to products, deformation in a utilization process is avoided, and in a late utilization period, although small cracks probably occur, the saggar is high in integral strength and still can be used, and the service life is prolonged from 3 months to 5 months; in addition, the preparation method is simple, feasible and easy to implement.