The invention discloses an unmanned helicopter 
relay data link system. The unmanned helicopter 
relay data link system comprises a 
relay unmanned helicopter module, a 
base station module, a 
ground station module, a remote controller module, a 
wireless transmitting module, a 
wireless receiving module, a relay unmanned helicopter main controller module and a target unmanned helicopter main controller module. The invention also discloses a control method for controlling the unmanned helicopter relay 
data link system. The control method comprises the following steps: 1, outputting the parameters of a controller and transmitting the output parameters to the 
base station module via a UDP network protocol by the 
ground station module; 2, encapsulating acquired flight 
control data and task data into one data frame by the 
base station module; 3, extracting the 
flight data and the task data in a data part respectively; 4, comparing the destination address of the data frame with the local address of an unmanned helicopter; 5, acquiring sensor data; and 6, after the base 
station module receives downlink data packets, forwarding the received downlink data packets to the 
ground station module. The unmanned helicopter relay data link system has the advantages of low communication cost, 
high transmission efficiency, high generality and the like.