The death-toll of the 1970 Tonghai earthquake in Yunnan province is the largest only after the Tangshan earthquake and the Wenchuan earthquake since 1949.15 621 persons lost their lives in the earthquake. As it occurred in a particular historical period, the historical situation of the earthquake was questioned by some people in society. The results of these queries belittled part work about the earthquake, for they were in conflict with the conclusion made in the past. Therefore, in this paper aiming at the location, magnitude, casualties, releasing form of the earthquake and other related problems, we researched and analyzed the documents and archives, and then attempted to reply to the questions and drew a conclusion from real historical truths.