A method for in-situ measuring electrical properties of carbon nanotubes includes placing a first electrode in a chamber, wherein the first electrode defines a cavity. A growth substrate is suspend inside of the cavity, and a catalyst layer is located on the growth substrate. A measuring meter having a first terminal and a second terminal opposite to the first terminal is provided. The first terminal is electrically connected to the first electrode, and the second terminal is electrically connected to the growth substrate. A carbon source gas, a protective gas, and hydrogen are supplied to the cavity, to grow the carbon nanotubes on the catalyst layer. The electrical properties of the carbon nanotubes are obtained by the measuring meter.