A secret sharing scheme in halftone images is proposed in this research. Given a secret halftone image, several gray-level images with the same resolution will be chosen from the database to collaboratively carry the secret information. The selected images will be transferred to halftone ones using Multi-scale Error Diffusion (MED), with the constraint imposed by the pixels of halftone secret image. The modified MED ensures that the resultant pixels of host halftone images should satisfy the required conditions such that collecting all the processed halftone images can successfully reveal the secret one. In addition to facilitating the perfect extraction of hidden information, maintaining the quality of all the halftone images in this secret sharing scenario is the other major objective, which is achieved by the usage of MED and selection of suitable host images. The experimental results demonstrate the satisfactory performance of the proposed method.