Indentation forming process is used for internal forming and sizing of thick-walled tubes working in high internal pressures. In this process, a mandrel with a diameter slightly larger than that of the tube is pressed and moved inside the tube, creating an internal profile. This article presents theoretically and experimentally influences of longitudinal ultrasonic vibration on this forming process. For this purpose, vibro-impact and continuous forming regimes have been investigated. Application of longitudinal ultrasonic vibration along the axis of the workpiece showed experimentally reduction of 15%-21% of axial forming forces and improvement of surface quality of the bore of the tube, while no effect on spring back of the formed zone was observed.