The invention discloses a preparation method for a nano titanium carbide particle reinforced biological magnesium-based composite material. The preparation method is characterized in that a prefabricated part is added into a liquid-state magnesium alloy, magnesium alloy melt which is doped with a nano titanium carbide particle prefabricated part and is heated to a temperature of 70 DEG C higher than a melting point is synchronously applied with mechanical stirring under ultrasonic vibratory action, so that the uniform distribution problem of nano titanium carbide particles is effectively solved, and uniform distribution of the added nano titanium carbide particles is realized; the as-cast nano titanium carbide particle reinforced biological magnesium-based composite material obtained in the first step is put into a processing mould to heat and preserve the heat, and ultrasonic composite variable-temperature hot pressing is performed, so that high-density lattice defects are caused inside the material; moreover, in the ultrasonic composite variable-temperature hot pressing process, grain refinement can be promoted by ultrasonic waves, and nano particles can prevent magnesium alloy grains from growing; and under action of ultrasonic composite variable-temperature hot pressing and nano particles, strength and toughness of the nano titanium carbide particle reinforced biological magnesium-based composite material can be remarkably improved.