China bears a large burden of global maternal mortality, and the largest burden of maternal deaths in China is in poor western provinces. This study aimed to investigate the trends in maternal mortality and its associated factors in Guizhou province of western China between 1996 and 2009, and examine differences between minority and non-minority counties. A population-based, longitudinal, retrospective study was performed in a poor western province of China with a considerably large ethnic minority population. All 86 counties/districts of Guizhou were included with population at county, township and village level. Maternal mortality data were collected from routine reporting database of Guizhou Provincial Health Bureau. Trend and comparative analyses and multivariate linear regression analyses were performed using SPSS 17.0. Maternal mortality ratio(MMR) and its change over time, differences between ethnic groups were analyzed. A declining trend in maternal mortality and rising trend in hospital delivery in Guizhou was observed; ethnic differences between two ethnic groups persisted. The reduction in maternal mortality between 1996 and 2009 was related with increased gross domestic product, decreased male illiteracy rate, and increased hospital delivery rate. We found the declining trends in maternal mortality in Guizhou with persisting ethnic differences. The declining trends are related with economic development, hospital delivery and male illiteracy. Effective health education on maternal health is urgently needed for the minority groups, and basic education for the new generation should be enhanced to eradicate the illiteracy. China bears a large burden of global maternal mortality, and the largest burden of maternal deaths in China is in poor western provinces. This study aimed to investigate the trends in maternal mortality and its associated factors in Guizhou province of western China between 1996 and 2009, and examine differences between minority and non-minority counties. A population-based, longitudinal, retrospective study was performed in a poor western province of China with a urged large ethnic minority population. All 86 counties / districts of Guizhou were included with population at county , township and village levels. Maternal mortality data were collected from routine reporting database of Guizhou Provincial Health Bureau. Trend and comparative analyzes and multivariate linear regression analyzes were performed using SPSS 17.0. Maternal mortality ratio (MMR) and its change over time, differences between ethnic groups were analyzed. A declining trend in maternal mortality and rising trend i n hospital delivery in Guizhou was observed; ethnic reduction between maternal mortality between 1996 and 2009 was related with increased gross domestic product, decreased male illiteracy rate, and increased hospital delivery rate. We found the declining trends in maternal mortality in Guizhou with persisting ethnic differences. The declining trends are related with economic development, hospital delivery and male illiteracy. Effective health education on maternal health is urgently needed for the minority groups, and basic education for the new generation should be enhanced to eradicate the illiteracy.