Ben-Tor was born as Kurt Winter in the Baltic city of Königsberg, East Prussia, Germany, (since 1945 Kaliningrad, now in Russia) in 1910.

With the rise of the Nazi Party in Germany, he emigrated to the then British Mandate of Palestine (now Israel) in 1933, where he later hebraicized his name.

Ben-Tor joined the Geology Department at the Hebrew University of Jerusalem, and continued on to doctoral studies in Switzerland, where he was erroneously arrested at the outbreak of the Second World War on suspicion of being a German spy, but he managed to flee home to Mandate Palestine.

Ben-Tor served from 1944-1948 in the state-to-be's Provisional Council, as a member of the Aliyah Hadashah Party, comprising immigrants from Germany.

He was also active in the Haganah (the underground Jewish defence force) and was asked to serve in Hemed, its Scientific Division, by Professor Yisrael Dostrovski.