The averaging effects of a probing signal on moving target detection radar are analyzed by reviews and simulations. The reviews of radar signal processing show that an averaging interval never exceed the half-period of a maximum Doppler frequency and corresponds to a very small portion of the radar range resolution, provided that a probing signal and a processing are properly designed to acquire an expected maximum target velocity without an aliasing. And, simulations using a linear frequency modulation (LFM) based probing signal at the above properly designed case indicate below two things. The first is an averaging on moving target detection brings always a positive effect and the improvement of a detection performance on the expected fastest moving target is about 3 dB less than that on a slow moving target. The other is, for a given averaging interval, more times averaging of shorter signal and less times averaging of longer signal have similar effect for the improvement of a detection performance.