Similarity measurement of business processes is a basic operator which is useful in several scenarios, such as business process management, business process searching, business process re-engineering and so on. Firstly, the framework of the methodology is proposed; secondly, two kinds of trace generation method is discussed; thirdly, the measurement of trace similarity is studied from information theory perspective; fourthly, the parallel algorithm to compute similarity of business processes is described based on MapReduce; at last, the experiments is illustrated and the conclusion is drawn.