Understanding the nature of pi-electron density is important to characterize the conjugate pi molecular systems. In this work, the pi-electron densities of some typical conjugated pi molecular systems were separated from their total electron densities; the positions and natures of non-nuclear (3, -3) pi-attractors and the pi-bond critical points (pi-BCPs) are investigated. The calculated results show that for the same element, the position of the pi-attractor is constant, regardless of the chemical surroundings. The position of the pi-BCP is closer to the atom with the larger electronegativity. (C) 2017 Elsevier B.V. All rights reserved.