During vector predictive coding of digital signal series, the vector signal series, obtained by grouping adjacent samples of sources signal series, can approximate to a vector autoregressive series with stable covariance. This paper, applying the orthogonal projection principle of Hilbert space, attempts to formulate a vector predictive coding strategy highly capable of parallel processing and to deduce from this strategy an adaptive parallel processing algorithm, which, compared with traditional lattice algorithms, has improved remarkably in calculation complexity and storage space.