The invention discloses a laser-assisted III-V group crystal growth device which comprises a reaction kettle, a reactant solution contained in the reaction kettle, a seed crystal template impregnated in the reactant solution, a laser emission device, a laser receiving device, a laser incident window and a laser emergent window. The invention also discloses a laser-assisted III-V group crystal growth method which comprises the following steps: placing the seed crystal template at a specific position, i.e. a laser path, in the reactant solution, and assisting a crystal liquid phase in the reactant solution in epitaxial growth by adopting laser of which the frequency is the same as the atomic resonance frequency or molecular resonance frequency of crystals in the crystal growth device or a growth raw material. According to the device and the method, the reaction rate can be effectively increased, the quality of the crystals can be effectively improved, and the controllability is high.