An electronic microscope includes a carrier, a first driving unit, a flow-buffer unit and an electron source. The carrier carries a sample. The first driving unit drives a first fluid to flow along a first flow path, wherein the first flow path passes through the sample. The flow-buffer unit is disposed on the first flow path to perform buffering on the first fluid, wherein the first fluid flows through the flow-buffer unit and the carrier in sequence. The electron source provides an electron beam to the sample.