This paper makes a numerical investigation on the spurious eigenvalues problem by the non-dimensional dynamic influence function (NDIF) method for plate vibration problems. We find that the NDIF spurious eigenvalues of plate vibration problems are often related to the eigenvalues of the corresponding membrane or plate, and vary with boundary conditions in the tested examples. It seems that we cannot simply identify the spurious eigenvalues of a practical problem. But, fortunately, through numerical experiments, we have obtained a few observations of the spurious eigenvalues in dealing with the plate vibration problems, which can be helpful in the practical application of the NDIF method. (C) 2009 Elsevier Ltd, All rights reserved.