From 2010 to 2015, the Wuhan Institute of Posts and Telecommunications (WRI) had undertaken the national key basic research development program project ‘ultra-high speed, ultra-large capacity, ultra-long distance (3U) optical transmission based research’ as the leading agency. Under the support of the project, we have obtained a series of achievements in scientific research and engineering. Some of the results have been widely used in commercial systems. This Review will make a preliminary summary of the achievements during the past 5 years.