African Arguments posted on 19 December 2016 a brief analysis titled "We May Have Been Massively Overestimating the Number of Chinese Migrants in Africa" by Hannah Postel, migration researcher at the Center for Global Development in Washington.
This analysis, based on a year of research in Zambia, looks specifically at the number of Chinese migrants in Zambia. An estimate of 80,000 has commonly been used for Zambia. Her research suggests the actual number is between 13,000 and 23,000. There is also a problem of definition. What constitutes a migrant? Obviously someone who moves permanently qualifies. But what about laborers contracted to work on infrastructure projects, nearly all of whom return to China, and even small traders who may or may not remain for an extended period of time? Senior Chinese officials often use the estimate of one million Chinese living in Africa. But this number too is guesswork.
AFK Insider published on 19 January 2017 an article titled "20 African Countries with the Most Chinese Migrants, And Why These Statistics Are Problematic" by Dana Sanchez. The article provides an estimate of the number of Chinese migrants for 20 African countries.
This article is correct in emphasizing the problematic nature of the numbers of Chinese migrants in Africa. Based on my own experience in asking this question while travelling around Africa, the estimates vary widely. I found that the Chinese embassy consistently had the lowest estimate because it tended to be based on Chinese actually registered at the embassy and many Chinese do not register. Other Chinese and African sources usually had much higher numbers, some ridiculously high. If one includes temporary Chinese laborers in the numbers, the figure can vary enormously from one year to another. As a project is completed, the number falls significantly and as one begins, the number rises.