Though in Sanjiazi Village where Manchu language is best preserved in China now, the language used is in a serious declining state than before as there are only few elder Manchu people who can speak fluently. In less than fifty years from 1960s to early of 21st century, Manchu language used in Sanjiazi has undergone a declining course from a communicative language to an endangered one. Based on the statistics and materials from the fieldwork of other researchers in different times and the author, this paper tends to study the actual changes of the spoken Manchu in Sanjiazi Village and discusses the major causes of change.