Java Memory Trajectory Forecasting is the primary work for energy consumption optimization of memory management system on Java platform. Based on the characteristic of Java memory management, this paper analyzes a large number of memory trajectory data of typical Java applications. On the conclusions obtained from the analysis, this paper designs a prediction algorithm with the combination of memory allocate rate and working memory for Java program memory trajectory and achieves higher prediction accuracy. This work has a significant importance for both Java application performance optimization and Java memory management system energy consumption optimization on Java platform.