Effects of rotation speed on the microstructure and transformation behavior were investigated for Ti-48at%Ni melt-spun ribbons. The Ti-48at%Ni shape memory alloy ribbons were fabricated by the melt-spinning method with various rotation speeds ranging from 2500rpm to 7500rpm. The melt-spun ribbons were completely crystallized to TiNi B2 phase during solidification at lower rotation speeds less than 4000rpm. Amorphous and B2 phase coexisted in the melt-spun ribbons fabricated at higher rotation speeds of 5000rpm and 7500rpm. The martensitic transformation behavior was investigated both in the as-spun and heat-treated ribbons. The transformation temperature increased with decreasing cooling rate and increasing heat-treatment temperature.