The invention provides an adaptive radiation source modulation identification method based on time-frequency analysis. The method comprises the steps of I, carrying out time-frequency analysis on a received radiation source signal by use of time frequency distribution, converting the radiation signal from a time-domain signal to a time-frequency two-dimensional image; II, reducing computation complexity and characteristic dimension by use of an image processing technology, and improving the proportion of signal characteristic information in the image through normalization, binaryzation, image thinning and image preprocessing operations; III, carrying out image shape characteristic extraction on the preprocessed image in combination with a second-order and four-order moment estimation method by use of an adaptive principal component analysis algorithm; and IV, identifying a modulation mode of the radiation source signal by use of an LIBSVM (Library for Support Vector Machine) classifier. According to the adaptive radiation source modulation identification method based on time-frequency analysis, the characteristic missing of a low signal to noise ratio signal can be effectively avoided, and characteristic redundancy of a high low signal to noise ratio can be also avoided, and the modulation identification rate is not affected at the same time.