A wafer cassette transportation method includes the steps: (a) Provide a monitoring system, overhead platforms, a detection system, and a plurality of transportation systems; (b) The detection system detects whether or not any overhead platform has a wafer cassette and generates and transmits first signals to the monitoring system; (c) The monitoring system reads the first signals and instructs one of the transportation systems to move the wafer cassette to an empty overhead platform; (d) The detection system detects whether or not any overhead platform has a wafer cassette and generates and transmits second signals to the monitoring system; and (e) The monitoring system reads the second signals and instructs another transportation system to move the wafer cassette away from the overhead platform, so as to enhance the transportation speed of the wafer cassette and lower the manufacturing cost. The present invention further provides a wafer cassette transportation system.