Nanocrystalline GdFeO3 and Gd3Fe5O12 powders were prepared successfully by sol-gel auto-combustion method using a glycine-based gel. The as-prepared GdFeO3 and Gd3Fe5O12 powders presented spherical shape, and composed of continuous porous network structure due to the releasing of a large amount of gases during auto-combustion process. This special microstructure was significant for reducing the magnetic interactions between nanocrystalline powders. The Gd3Fe5O12 samples presented ferrimagnetic feature at low temperatures. At 10 K, the saturate magnetization is about 87.9 emu/g. As temperature increased to 300 K, the magnetization decreased rapidly since the thermal fluctuations changed the main magnetic spin ordering. The GdFeO3 samples presented antiferromagnetic feature at 5 K, and the magnetization reaches 109 emu/g at 50,000 Oe field. As temperature increased to 300 K, the antiferromagnetism decreased rapidly, and the magnetization curve presents linear tendency due to the dominant paramagnetism contribution of Gd3+ ions.