Dry-wet spells and weather cycle probability models are presented for the daily rainfall series at five representative stations in eastern China based on Markov chain theory. Some valuable statistical parameters, such as the mean length and variance of the dry-wet spell, the mean length and variance of the dry-wet cycle and the limit distribution probability of the dry-wet day evolution, are calculated. The results reflect the characteristics of the monsoon climate in eastern China and provide the climatic basis not only for agricultural production and water resource utilization but also for daily weather forecasting.