In the present work, a unidirectional crystal of Heusler Mn50Ni37In10Co3 alloy was fabricated using a modified high-pressure optical zone-melting furnace. Lower martensitic transition temperature, higher saturation magnetization and enhanced magnetic refrigeration capacity were discovered via Co doping compare to Mn50Ni40In10 we has already reported. The compositional dependence of the martensitic transition temperatures along the crystal growth direction is mainly attributed to the axial compositional distribution about Mn, Ni, In and Co. Different positions has different compositions and working temperature range(ΔTFWHM). Experimental results showed that relative cooling power was improved, expanding the limited temperature span in practical application.