The embodiment of the invention discloses a test method and a device of signal period. The method in the embodiment of the invention comprises the following steps: getting the estimated signal period of the current signal frame; determining the possibility of wrong judgment of the estimated signal period according to the relation between the signal period of the previous signal frame and the estimated signal period; if wrong judgment exists, judging whether the judgment parameter is more than the judgment threshold, if so, defining the signal period of the previous signal frame as that of thecurrent signal frame. The embodiment of the invention is easy to calculate and has no extra algorithmic timelag.