Prof. Zhang is currently a Professor in the School of Economics, Zhejiang University. He is also Wei Lun Professor of Economics in the Department of Economics, The Chinese University of Hong Kong. Before returning to Hong Kong, he was Assistant Professor in the Department of Economics, University of Western Ontario. He is a Fellow of the Econometric Society. He received a B.Sc. in Engineering from Zhejiang University in 1983, and an M.A. and Ph.D. both in Economics from McMaster University in 1986 and 1990, respectively.

His research (both theoretical and empirical) has focused on the economics of family behaviour, including crime, fertility, marriage, education, intergenerational transfers, marital transfers, gender bias, and old-age support. He also works on family-related macro issues, such as ageing, social security, and economic growth. Using many data sets from different countries (regions), either micro or macro, he has studied economic issues in Canada, the US, the Philippines, Taiwan, Hong Kong, as well as Mainland China. 

He has published over 100 papers in major refereed international journals. Many of them were published in leading economics journals such as Journal of Political Economy, Review of Economic Studies, Economic Journal, Review of Economics and Statistics and International Economic Review, or in leading field journals such as Journal of Labor Economics, Journal of Public Economics, Journal of Development Economics, Journal of Human Resources, and Journal of International Economics. According to a ranking by RePEc dated May 2018, Junsen Zhang ranks as the number one economist in the field of the Chinese economy. 

He has been Co-Editor of the Journal of Population Economics since 2001 and Journal of Human Resources since February 2019, and had been the President of the Hong Kong Economic Association from 2007 to 2011. In 2013, he was elected as a Fellow of the Econometric Society. In 2017, Junsen Zhang and his coauthor, Mark Rosenzweig, received the Sun Yefang Award Economic Science Award, one of the highest honors in the field of economics in China, for their article Do Population Control Policies Induce More Human Capital Investment? Twins, Birth Weight and China's 'One-Child' Policy.