The invention relates to a land surface evapotranspiration measurement system which is characterized in that the land surface evapotranspiration measurement system comprises a cart carrying module, alever attenuation module, a PLC motion control module, a data acquisition module and a power supply and communication control module, wherein, the cart carrying module is used for carrying the systemto the position which is below a container to be measured and bearing the weight of the container to be measured, the lever attenuation module is used for balancing the partial weight of the containerto be measured, the PLC motion control module is used for controlling the motion of the cart carrying module, the data acquisition module is responsible for testing the weight of the container to bemeasured and transmitting test data to the power supply and communication control module, and the power supply and communication control module is used for supplying power and sending control commandsto the cart carrying module, the PLC motion control module and the data acquisition module. The land surface evapotranspiration measurement system overcomes the shortcomings of the prior fixed type and the hanging type weighing systems of evapotranspiration instruments and integrates the advantages of the two, so that the land surface evapotranspiration measurement system can be widely applied inscientific research fields of agriculture, forestry, water conservancy, meteorology and the like.