This research examined the relationship among social withdrawal types, mutual friends, friendship quality and loneliness in middle childhood. 571 children from Grade 3 to Grade 6 participated in this survey. From Grade 3 to Grade 6 the loneliness of all types of ,social withdrawal children descended. The loneliness of passive withdrawal children was lower than that of active isolation children. Different types of social withdrawal children had significant difference in the number of mutual friends, intimate exchange and companionshlp-recreation...