A cyclic iteration structure pseudo-random sequence generating method based on combined LFSR and chaotic systems is presented. Firstly, a choice function is chosen based on LFSRs computing result, and the selected chaotic function is used for generating the corresponding chaotic sequence by using iterative computation. The chaotic sequence is processed by binary system transformation, and the generated binary sequence is output as the end pseudo-random sequence. At the same time, the generated binary sequence is used as feedback value and operates with the LFSRs feedback value, the corresponding result is taken as the final feedback of LFSR. This process can achieve random perturbation of LFSR. And a real number pseudo-random sequence generating method is also presented. Performance of pseudo-random sequence generated by using our method is also analyzed by experiment, and simulation results show that the generated sequences have qualities of randomicity and security.