Abstract: Research was conducted on object segmentation of the interactive information comprising prior knowledge between user and system. An interactive object segmentation algorithm was proposed based on an active contour without an edge (CV) and the prior shape. Due to imprecision in the prior shape user inputs, a weighted pix algorithm based on gradient and Laplace was introduced. To overcome problems with object contour shrink, a new area actuator was introduced. The proposed algorithm did not need a prior knowledge model obtained by training based on accurate prior knowledge. The user only needed to choose an approximate region of object segmentation, and the algorithm was able to segment the region. Given the selected gray scale levels, the iterative frequency was only about 26.4% of the basic CV model.