CCAST, World Lab, Beijing 100080, Peoples R China
; Henan Normal Univ, Dept Phys, Xinxiang 453002, Henan, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
The O(alpha(s)) corrections to the inclusive semitauonic B decay are calculated in a one-generation technicolour model. Comparing the theoretical prediction with the recent experimental results, we present a stronger constraint on the masses of the charged colour-singlet pseudo-Goldstone bosons, m(p) > 58 GeV at 95% confidence level.