The effects of ultrasonic vibration and heat treatment on the microstructure and tensile properties of laser direct forming IN718 superalloy were investigated. The results show that microstructural grain size became finer due to the actions and influences of ultrasonic vibration. In addition, the microhardness and tensile strength of the parts fabricated by LDF with ultrasonic vibration were higher compared with that of the ones fabricated by LDF without ultrasonic vibration. With the heat treatment of homogenization, solution and double aging, the columnar dendrites changed to equiaxed grains due to recrystallization. Laves phase dissolved, and there were grainy and acicular δ phase distributing in and along boundaries of the grains. Besides, a large number of strengthening phase γ″ and γ′ separated out on the matrixes. The room-temperature tensile properties of heat treatment samples reached the wrought standard of Q/3B 548-1996.