Aiming at the problem that accuracy of the bigdelayer based on asynchronous doublememorytechnologyis hard to be advanced. This paper proposes a realtime selfcorrecting method. Selfcorrecting makes full use of the roughfine two stage delay of asynchronous doublememory to make the closedloop measurement in fine stage, and correct in rough stage. Selfcorrecting was realized with the digital resource not in use of Bigdelayer, which realized high accuracy delay with low consumption and low costing without disturbing the delayer when it working. A principle of selfcorrecting was proposed on deeply researching asynchronous doublememory technology, and the method of how to implement selfcorrecting was introduced, contrast test was conducted to prove that the realtime selfcorrecting technology can really advance the accuracy.