On May 28, professor Ingo Witt from Georg-August-University of Goettingen, Germany, made an academic lecture about the principal symbol map for 2-microloacal operator. In the lecture, the professor reviewed the previous studies about microlocal analysis, and introduced and analyzed the major mathematical problems and the hot issues of partial differential equation in which he showed special interest . Professor Ingo Witt has published 30 papers in world prestigious journals about partial differential equation and microlocal analysis.