Frequency multiplying circuit for clock signal is provided, including N branches and an N-times frequency multiplying circuit, wherein each branch includes a buffer and a frequency doubling circuit, and the frequency doubling circuit doubles a frequency of a reference clock signal to obtain a frequency doubled reference clock signal, wherein the N-times frequency multiplying circuit includes: N second calibration delay circuits coupled to the N frequency doubling circuits respectively, wherein each second calibration delay circuit performs clock delay on the frequency doubled reference clock signal to obtain a clock delayed frequency doubled reference clock signal; and an N-path phase combination circuit coupled to the N second calibration delay circuits, and configured to perform phase combination on the N clock delayed frequency doubled reference clock signals to obtain a 2N-times frequency multiplied reference clock signal. Cost is reduced, and phase noise of a multi-times frequency multiplied reference clock signal is optimized.