Abstract: In this paper， with respect to the low reactive activity of ludwigite from Wengquangou for the manufacture of borax by the CO↓2-soda process，a kind of composite additive was employed for the calcination of ludwigite.The reactive activity of calcined ludwigite can be evaluated by the alkaline hydrolysis ratio at atmospheric pressure.The effects of composite additive dosage，calcining temperature and calcining time on the reactive activity of calcined ludwigite were studied respectively.The results showed that the reactive activity of calcined ludwigite in the CO↓2-soda process was obviously increased after the sodium activated calcination by using the composite additive.The optimum process conditions were that the composite additive quantity was 19% by weight of original mineral，calcining temperature 950 ℃ and calcining time 2 h.The reactive activity of calcined ludwigite from Wengquangou reached 93.16%.