A chemical vapor deposition (CVD) apparatus is provided. The CVD apparatus includes a CVD chamber including multiple wall portions. A pedestal is disposed inside the CVD chamber, configured to support a substrate. A gas inlet port is disposed on one of the wall portions and below a substrate support portion of the pedestal. In addition, a gas flow guiding member is disposed inside the CVD chamber, coupled to the gas inlet port, and configured to dispense cleaning gases from the gas inlet port into the CVD chamber.