The relations among the morphological parameters of binary polymer blends with the morphology of well-dispersed particles are quantitatively studied to correct the error from the simple cubic (sc) lattice assumption made in previous works. A new morphological parameter, the particle spatial distribution parameter xi, is defined. A new equation for correlating the spatial distribution with other morphological parameters is derived. The relationships among them are discussed. The values of the spatial distribution parameter for poly(vinyl chloride)/nitrile rubber, polypropylene (PP)/EPDM and PP/EVA blends appear to be a constant. The errors stemming from the sc lattice assumption for these blends are analysed.