In this paper, a 3D printed multilayer microstrip line structure with vertical transition is designed, fabricated and characterized. The dielectric part of the structure is printed using the FDM method and the conductor part is printed using the ultrasonic wire embedding approach. The measured total insertion loss of the 3D printed multilayer microstrip (90 mm long) including the vertical transition is smaller than 2 dB below 6 GHz. The measured results agree well with the simulation. The performance of this structure demonstrates that 3D printing techniques may be able to realize functional multilayer RF components / systems. As an example, a 3D printed multilayer phased array is designed based on similiar microstrip and vertical transition structure in this work. The simulated results show good impedance matching around 3.5GHz and a high directive beam at expected direction.