The traditional data management, data representation, storage and indexing, querying, mining and all other technical can not be directly applied to the similarity search of time series data with uncertainty. Our work study for other theories and technologies, the uncertainty of time-series data for the complexity of the structure, and for the first time we give the formal definition of probability nearest neighbor search over uncertain time series database; the PLA dimensionality reduction over time series of uncertainty. After conversion to the PLA space, we propose three lemmas to accelerate the search efficiency; based on three lemmas the appropriate searching algorithm PKNNS is also given. A serials of experiments are also made to test the effectiveness and efficiency of algorithm PKNNS.