While promoting economic growth and creating employment, China’s exports also have impacts on its domestic ecological environment. How to measure the relative contribution of exports to different fields, so that the unbalanced development could be mitigated, has become an important issue. This study adopts the socially-and environmentally-extended multi-regional input-output model to analyze the employment and CO2 emission effects of exports on Chinese provinces in 2012-2016, from the perspective of the division of labor in value chain, based on which, the imbalance in the relative contribution of exports to Chinese provincial employment and CO2 emissions is further explored. Results show that the mode in participating value chain determines that the contribution rate of exports to CO2 emissions is significantly higher than that of employment. Temporally, the imbalance has been broadened between 2012 and 2016. Spatially, the imbalance is more significant in the central and western provinces. Therefore, to improve the social benefits of exports while reducing its adverse impact on the environment, it is necessary to give play to regional comparative advantages to accelerate the optimization and transformation of Chinese provinces’ participation mode in the value chain.