A miniaturized microwave sampler has a first substrate and a second substrate mounted together on a mounting surface, a ground layer formed on the mounting surface, a slot-line formed on the ground layer. A first microstrip line is formed on a top surface of the first substrate and has a first end as a local pulse signal input port. A T-shaped second microstrip line is formed on a bottom surface of the second substrate and achieves an electromagnetic coupling with the first microstrip line through the slot-line. The second microstrip line has a longitudinal segment and a latitudinal segment both being perpendicularly connected together. The longitudinal segment has one end as a radio frequency signal input port. The latitudinal segment further extends to form two output ports.