The invention relates to a method and device for enhancing the downlink synchronization reliability. The method disclosed by the invention comprises the following steps: obtaining parts of the data of a synchronous downlink (SYNC-DL) code in the data of each subframe, relating to a local SYNC-DL code of user experience (UE) and calculating a parallel data processing (PDP) value; calculating a noise threshold; searching the peak value of the PDP value of each subframe and also recording the position of the peak value; and regulating the position of a frame header of a current subframe according to the deviation of the position of the peak value of the PDP value of the current subframe and an ideal position when the position difference of the peak values of a previous subframe and a posterior subframe is smaller than the threshold of the peak value and the peak value of the PDP value of the current subframe is also greater than the noise threshold. According to the method and device for enhancing the downlink synchronization reliability, the relation of parts of the data of the SYNC-DL code in the received subframe data and the sequence of the local SYNC-DL code is adopted to search the relevant PDP peak value so as to realize downlink synchronization. The reliability of the position of the peak value of the current frame header is distinguished by the comparison of a relevant energy peak value and the noise threshold and the difference of the positions of the peak values of the previous subframe and the posterior subframe, and the accuracy of downlink synchronization regulation under a scene with a comparatively poor channel environment is enhanced, so that the stability of a system is enhanced.