Live combat training simulates the process of weapon attack and damage based on real military installation. Its essence is multi-platform distributed real-time simulation， and time unity is the primary basis. Based on time unified demand of real combat training， fully considering the training process， information transmission and time basis of platforms， this paper develops time unified technical research. The time unity design is mainly designed from two levels of participation platform time synchronization and training information time alignment， and time consistency verification is carried out periodically to enhance the system robustness and consolidate the foundation of time unity. In this way， the time of whole process and cross-domain multi-platform distributed real combat training can be unified.