The invention relates to a single tone frequency estimation technology, in particular to a variable length-iteration operation-based single-tone signal frequency estimation method. For a sinusoidal signal of a single-tone signal to be estimated, wherein the actual frequency, the data length, the sampling rate and the calculating resolution ratio are described in the specification, the estimation frequency is obtained for the actual frequency by using an FFT (Fast Fourier Transform) definition, one frequency is respectively taken from the left side and the right side of the estimation frequency, the amplitude spectrum of the estimation frequency is compared with the amplitude spectrums of the left side frequency and the right side frequency, thus an iteration algorithm is carried out, and the amplitude spectrum of the estimation frequency is largest in the three reached frequencies, and the frequency estimation value described in the specification is obtained. The invention has the advantages of simple principle, high precision, high operation speed and easiness in engineering realization. Through continuously changing the length and using the iteration operation, the actual frequency value is gradually approached, and the optimal frequency estimation value is researched. The variable length-iteration operation-based single-tone signal frequency estimation method is widely applicable to multiple fields such as receiving end carrier estimation, signal analysis and the like; meanwhile, the estimation precision can be regulated through changing iteration step, thus the variable length-iteration operation-based single-tone signal frequency estimation method is convenient and flexible, and is more suitable for hardware platform processing.