Abstract: A new kind of calculation formula of goaf roof critical thickness was proposed based on thin plate theory.Used it as the core, a set of prediction and forewarning system of goaf safe roof thickness was developed combined with site actual requirement and adopted object-oriented thought and using Flex technology.Collection and input of goaf information are realized in this system, arrangement and maintenance of goaf information are completed, which could display goaf detailed information visually, and it can emphatically analyze the danger degree of goaf and alarmed in time.This system gets good effects in prediction and forewarning of a mine goaf.

Key words: Goaf, Safe roof thickness, Prediction and forewarning, RIA