The microstructure and phase composition of Gd5Si2Ge2 alloy obtained by arc-melting and melt spinning processes were studied The results show that the arc-melted Gd5Si2Ge2 samples with different mass had different microstructure and phase composition. The Gd5Si2Ge2 alloys melt-spun under the velocity less than 40 m/s crystallize in the Gd5Si2Ge2-type structure; and the sample under the velocity of 50 m/s consists of Gd5Si2Ge2-type and Gd5Si4-type phases. The effect of solidification rates on the microstructure and phase composition were identified.