The invention provides a testing 
system for loads of frequency 
converters, which comprises a power supply 
transformer, at least one testing module and a controller. The power supply 
transformer outputs at least one 
power supply voltage, each testing module comprises at least one frequency converter to be measured and a 
load testing cabinet, each 
load testing cabinet is used as a 
variable load to adjust output of the corresponding frequency converter to be measured and outputs corresponding alternating-
current voltage to an output end of the power supply 
transformer, the controller controls the magnitude of the 
load testing cabinet of each testing module when the load testing cabinet is used as the 
variable load, and accordingly the output of the frequency 
converters to be measured is adjusted by the aid of the load testing cabinets. A three-phase reactor is directly disposed at an output end of each frequency converter to be measured so as to realize filtering 
processing, and accordingly a running mode of each frequency converter with a 
motor load is simulated. In addition, the frequency 
converters with different 
voltage grades can be loaded and tested under the condition without the motors, residual 
electric energy is fed back to the output end of the power supply transformer to be recycled, and accordingly energy is saved.