Aiming at condition of many heavy-duty vehicles in troop ordnance equipments extremely needing of condition monitoring and maintenance, multi-technique monitoring method of vehicle engine was introduced based on motor oil state monitoring. Multi-technique including oil quality analysis, wear particle analysis and contamination were expatiated and compared in detail. In result, the multi-technique monitoring of oil maintenance idea was put forward. This oil maintenance idea provided the scientific basis for field in time overhaul and maintenance, condition-based maintenance. In conclusion, the application of oil multi-technique monitoring has an active signification for development and perfection of the ordnance equipment safeguard technique.