The past decades have witnessed obvious changes in transport in China’s cities in the context of urban transformation. One of the most serious changes to policy making is the increasing urban transport inequality. This study aims to explore the facts and factors about the social inequality in commuting by looking at Beijing as a case study. The results of analysis show that low-income people have longer commuting times than middle- and high-income workers. Car travellers have much less commuting times than metro or bus travellers. Personal and household characteristics are primary factors influencing workers’ commuting times, and less commuting time is related to higher household income. The jobs–housing balance and mixed land use could reduce low-income workers’ commuting times significantly. Institutional constraints created by the hukou system, social housing and the Danwei system tend to increase low-income workers’ commuting times and worsen social inequity in transport inequity. Since these institutions are not easily changed in a short period, social inequity in transport may increase in China’s cities in the next few years. Policies designed to reduce transport inequity are hardly efficient unless these institutional constraints are solved.