Channel calibration testing of electrically large planar digital phased array has extremely high requirements for the scale and quality of the microwave anechoic chamber. The limited speed of the scanning probe results in channel calibration tests conducted in microwave anechoic chamber lasting several hours. Further more, the temperature changes caused by prolonged testing can cause channel phased drift, leading to accurate test results. In response to the existing problems, this paper proposed an outdoor channel calibration testing method, and single calibration of all channels in the entire array only takes a few minutes, which can effectively solve the problem of channel phased drift caused by temperature changes caused by prolonged testing. By introducing a reference channel, the problem of receiving and transmitting difference in sources in outdoor calibration testing can be solved. This method not only effectively shortens the channel calibration time of electrically large planar digital phased arrays and improve the accuracy in test, but also reduces the time cost and microwave anechoic chamber hardware construction cost in the testing process. Finally, the feasibility and correctness of this method were verified through the Field test results of an electrically large planar digital phased array measurement and control system in Ka-band.