The invention provides an unmanned aerial vehicle system information transmission time delay test device and a method thereof. The device is characterized in that the device is formed by a photoelectric encoder (1) with a rotating shaft, a light emitting diode (2), a modified mouse (3), a photosensitive resistor (4), a test chip (5), an interface (6) which can be communicated with an airborne link device, an external crystal (7), a display module (8), a switch (9) and a power supply (10). According to the unmanned aerial vehicle system information transmission time delay test device and the method, the high precision external crystal is used as a clock source of timing, a test error is smaller than 1 ms through reasonable testing scheme and implementation steps, a testing result is reliable, a data support can be provided for the design of an unmanned aerial vehicle system by the scientific research personnel and the operation of an unmanned aerial vehicle by a ground station operator, and at the same time, the software and hardware design of the unmanned aerial vehicle system can be constrained further by the testing result.