The invention provides a modularized frequency synthesizing method based on direct digital and direct analogue combination, including the following steps: (1) direct digital frequency synthesizing method is adopted to generate M intermediate frequency marker signals with frequency interval of deltaF and bandwidth of (M-1)deltaF, namely F1, F1+deltaF, F1+2deltaF, ..., F1+(M-1)deltaF; (2) frequency shifting method is adopted to shift the frequencies of the M intermediate frequency marker signals generated in the step (1) to microwave frequency band, so as to generate M microwave local oscillation signals with frequency interval of deltaF and bandwidth of (M-1)deltaF, namely F2, F2+deltaF, F2+2deltaF, ..., F2+(M-1)deltaF; (3) indirect analogue frequency synthesizing method is adopted to generate N radio frequency marker signals with frequency interval of MdeltaF and bandwidth of (N-1)MdeltaF, namely F3, F3+MdeltaF, F3+2MdeltaF, ..., F3+(N-1)MdeltaF; (4) M microwave local oscillation signals generated in step (2) and N radio frequency marker signals generated in step (3) are subject to mixing, so as to obtain M*N frequency synthesis signals with frequency interval of deltaF and bandwidth of (MN-1)deltaF, namely F2+F3, F2+F3+deltaF, F2+F3+2deltaF, ..., F2+F3+(MN-1)deltaF, and the frequency synthesis signals are output. The invention realizes extremely rapid frequency conversion, extremely low phase noise and extremely low spurious level with low cost.