Abstract: This paper introduces Microcomputer-Based DTA/EGD/GC on-line coupled simultaneous technique and its constitution. Eleven different modes are controlled by keys. Multiple information aquisition, real time display and data processing are performed by microcomputer. Data compression and display technique moving screen are adopted. Many specific softwares for on-line coupled simultaneous technique have been developed. The analytical result which includes curves characteristic marked and tables is given. It gains satisfactory result to testing performances of the system with standard chemical samples. The system can be applied to the areas of catalyst, petro-addition, chemistry of coal, geology and mineralogy.