Based on the principle and specifications of Environmental Durability Test on automobile engine ECU, an open, intelligent and practical ECU durability testing system (EDTS) is designed. The system consisted of a simulation platform and a testing management software. The platform provided stimulating sensor signals and simulation loads, and an online automotive environment was built. The management software sent various instructions to set up the platform and read the ECU running status data. And this EDTS has been applied to test a kind of domestic automobile engine ECU．The experimental results shows that the mean time to failure (MTTF) of ECU samples was improved and the testing period was shortened greatly.