The invention provides a memory alloy driven by a magnetic field to deform and a preparing method of the memory alloy, and belongs to the field of shape memory alloys. The alloy has the capability that deformation is generated through control of an outer magnetic field under the room temperature condition and is a magnetic control shape memory alloy capable of generating recoverable strain under the room temperature condition through martensite twin boundary migration and reverse migration driven by the outer magnetic field changes. The chemical formula of the alloy is CoxNiyAlzFej, wherein x is larger than or equal to 28 but smaller than or equal to 42, y is larger than or equal to 25 but smaller than or equal to 32, z is larger than or equal to 23 but smaller than or equal to 37, j is larger than or equal to 0.5 but smaller than or equal to 10, the sum of x, y, z and j is 100, and x, y, z and j represent mol percentage content. Compared with existing materials, an Fe-Co intermetallic compound exists in a microstructure of the magnetic control shape memory alloy, the alloy has a wide magnetic-induced strain temperature range, large magnetic-induced strain capacity and good mechanical performance, and the magnetic control shape memory alloy can be importantly applied to the fields such as high-precision drivers and executers used at the room temperature.