The invention discloses a real-time PRF (Pulse Repeat Frequency) adjustment method for a spaceborne interferometric imaging altimeter. The method comprises steps: 1) in a uniform PRF working mode, thealtimeter searches a target echo by adjusting a search value and a search direction, and through echo gravity center tracking, the current target echo delay is obtained; 2) the altimeter is transferred to a pulse cluster working mode, teh value of the initial PRF is calculated by the current target echo delay, and through echo gravity center tracking, real-time PRF adjustment can be carried out.The method disclosed in the invention can realize quick capturing of the target echo and quick adjustment of the PRF, and has the advantages of being good in robustness and being applicable to wide range orbit changes of a satellite platform. The method of the invention has wide adaptability to altimeter observation targets and the method is applicable whether to observe a land or a sea, and seamless cohesion observation at a land-sea junction can be realized.