Recent Studies Show That Children from economically disadvantage families exhibit lower levels of cognitive functioning. The current research emphasises on this field by focusing on one mechanism that links material hardship to child out comes, namely the mediating effect of maternal depression. 1462 mothers in postpartum period in 1380 and 3 years later in 1383 respond to questionnaires including Denver Development Screening test and center for Epidemio Logical Studies, Depression scale in a longitude research program. Results show that maternal depression and poverty Jeopardized the development of child, especially for Cognitive development.