Guangxi Normal Univ, Coll Phys & Elect Engn, Guilin 541004, Peoples R China
; CAS, Inst High Energy Phys, Beijing 100049, Peoples R China
; Tsing Hua Univ, Dept Engn Phys, Beijing 100084, Peoples R China
; Kunming Teachers Coll, Dept Phys, Kunming 650034, Peoples R China
The strong coupling alpha(s)(s) is an important free parameter of Quantum Chromodynamics. Based on R values measured at BES, the values of the strong running coupling constant alpha(s)(s) at 2.0-3.7GeV are determined using the ss(alpha(3)(s)) and ss(alpha(4)(s)) order expressions calculated by pQCD, then alpha(s)(s) is deduced to the M-z. scale. The numerical prediction on the improvement of the uncertainty of alpha(s)(s) with the decrease of the experimental error of R value in the future experiment is also given.