The more precise extraction for the CKM matrix element |V_{cb}| in the heavy quark effective field theory (HQEFT) of QCD is studied from both exclusive and inclusive semileptonic B decays. The values of relevant nonperturbative parameters up to order 1/m^2_Q are estimated consistently in HQEFT of QCD. Using the most recent experimental data for B decay rates, |V_{cb}| is updated to be |V_{cb}| = 0.0395 pm 0.0011_{exp} pm 0.0019_{th} from Bto D^{ast} l u decay and |V_{cb}| = 0.0434 pm 0.0041_{exp} pm 0.0020_{th} from Bto D l u decay as well as |V_{cb}| = 0.0394 pm 0.0010_{exp} pm 0.0014_{th} from inclusive Bto X_c l u decay.
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