In order to devise scientific and sustainable development strategy, it is vital to assess the quality of economic growth. As a useful complement to traditional economic indicators, GPI's most reputed virtue is its great improvement in evaluating environmental and social costs. In this paper we estimate the GPI for all 31 provinces in mainland China from 1997 to 2016. GPI estimation is highly sensitive to income inequality, climate change damage, and depletion of non-renewables. We address contestable methodological assumptions associated with the three items which have been usually ignored in empirical studies. We use the Atkinson index in place of the Gini index as a measure of income inequality. We avoid the problematic duplicated counting of climate change damage and the unjustified cost escalation factor in depletion of non-renewables. Our results show that: first, GPI per capita has recently declined in some provinces, unveiling a threat to social welfare and sustainability; second, the “relative threshold effect”—the progress of social welfare promotion is slower than the expansion of economic scale—has been found in many provinces; third, resource consumption and environmental pollution, especially water pollution and carbon emissions, would generate substantial welfare losses.