The non-stoichiometric Ni50Mn27Ga23 polycrystalline ribbons were prepared by melt-spinning technique. The martensitic transformation and the magnetic-field-induced strain of melt-spun ribbons were investigated. The experimental results show that the ribbons still undergo thermal-elastic martensitic transformation and reverse transformation in cooling and heating process. The melt-spun ribbons exhibit typical thermo-elastic shape memory effect and larger strain than as-cast specimens, but martensitic transformation temperature decreases. The reason which makes melt-spun ribbons have larger martensitic-transformation-strain and magnetic-fieldinduced strain is that the particular internal stress induced by melt-spinning makes a texture form in the melt-spun ribbons. That the internal stress is released strongly by heat treatment results in a decrease of the magnetic-field-induced strain.