Professor Valerie Williamson, one famous international nematologist from the department of Plant Pathology of University of California, Davis, was invited by Professor Congli Wang, Research Leader of Agricultural Pest Control Group on June 17-24th, 2015. Her visit was supported by the State Bureau of Foreign Experts. She gave a talk to our scientists and students in Harbin District on June 18^th, 2015. Her presentation title was ‘The chemical ecology of root-knot nematode targeting to plant entry sites’. She introduced her team work from a few aspects: genomics and genetics of RKN, resistance and host range, and chemical signals: how nematodes respond to hosts and each other. Scientists and students actively communicated with Professor Williamson. During her visiting, Professor Wang introduced her research projects and progress. Her lab members introduced their own experiments and some interesting research results to Professor Williamson. She provided very helpful suggestions to the students and researchers in Professor Wang’s group. She also visited Hailun Experimental Station. Professor Xiaozeng Han gave a very detailed introduction about long-time experiments in the stations, which make Professor Williamson feel impressed about black soil and associated experiments in the station. Further discussion about the identification and application of chemical signals attracting nematodes were conducted between Professor Williamson and Professor Wang. The visiting of Professor Williamson definitely played a key role for further collaboration.