This is an announcement for the paper "The predual and John-Nirenberg inequalities on generalized BMO martingale spaces" by Yong Jiao, Anming Yang, Lian Wu, and Rui Yi. Abstract: In this paper we introduce the generalized BMO martingale spaces by stopping time sequences, which enable us to characterize the dual spaces of martingale Hardy-Lorentz spaces $H_{p,q}^s$ for $0<p\leq1, 1<q<\infty$. Moreover, by duality we obtain a John-Nirenberg theorem for the generalized BMO martingale spaces when the stochastic basis is regular. We also extend the boundedness of fractional integrals to martingale Hardy-Lorentz spaces. Archive classification: math.FA Mathematics Subject Classification: 60G46, 60G42 Remarks: 23pages Submitted from: jiaoyong@csu.edu.cn The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/1408.4641 or http://arXiv.org/abs/1408.4641