The differences between the two kinds of almanac in the new BDS civil navigation message and the navigation message of BeiDou-2 were analyzed, and the influence of various almanacs on the initial positioning time of the receiver was analyzed. Based on the actual data of almanac, the user algorithms of different almanac types were compared, and the influence of different age data on the initial positioning performance of receivers was analyzed. The results show that the performance of the precise ephemeris with a week of data is more stable, and the accuracy of medium accuracy almanac is lower than the accuracy of the precise ephemeris, but the performance can close to that of the precise ephemeris as a result of simplifying the message space. The contracted almanac further simplifies the parameter number and message space, although the location error achieved hundreds of kilometers, but can keep the corresponding precision after a few months, and shorten the initial positioning time of the receiver.